MBC is currently advocating the police to reinvestigate alleged crimes that happened inside Burning Sun, other clubs owned by Yang Hyun Suk and to investigate crimes committed by the key figures involved. 

They have also putted forward accusations, based on evidence in form of detailed testimony, that the founder of the agency YG Entertainment, Yang Hyun Suk, mediated prostitution services for foreign investors in July 2014.

This allegations have been denied by YG Entertainment as they've told that the founder indeed was present, but wasn't involved in these services and only knew Madame Jung out of the 25 women. 

Source (1) (2)

Other allegations have now also been presented by MBC 'Straight';

First witness:

A witness, Miss B, who used to work as an underaged prostitute for clubs in Gangnam gave her testimony. She revealed details, such as being paid around 300,000 won (~$250 USD) for sexual relationship at the club and 500,000 won (~$420 USD) for leaving with the VIP customer. The club's MD (Merchandiser) would pay the girls in cash, and set up the underaged girls with important VIP customers.

The girls was usually living on the streets, since they ran away from home, and some was even middle schoolers aged 14 years old. 

"The VVIPs who spend 10 million won (~$8,500 USD) would specifically ask for underage girls, and they’d take the girls to designated apartments, where they drug them and film themselves sexually assaulting them. They call these videos “pornos”, and the girls were given 1 million won to do this.

They say it’s easier to find drugs than cigarettes at Gangnam. It’s the worst. You ruin your body and lose your mind too. There are kids who move on to work at room salons, and some stay to work at the club because they still haven’t paid off their debts.

Needles are a given at the apartments. If you do drugs and film a porno, you earn about 1 million won (~$850 USD).

The most valued customer gets to pick who they want and they chose a girl who’s only 14.

The VIPs all know that we’re underage. They specifically ask for underage girls. If an MD tricks the VIPs with a girl who’s not underage, they don’t get paid."

— Miss B (witness & former underaged prostitute)

Source (3)

Second witness:

There's also another witness, a former employee at Club Arena. This club have previously been under scrutiny for having evaded tax laws and being the club where Seungri is accused to have mediated prostitution to investors. 

Source (4)

The former employee worked as an MD (Merchandiser) at this club and testified to how cremation teams would be assigned work in the group chats by upper management. They would cremate (clean up) tables, seats, and rooms after VIPs had sex inside the club.

Third witness:

Another witness, a former employee of Burning Sun came forward with more accusations. The allegation is how women were drugged, raped in the bathrooms and left behind unconscious by VIPs at Burning Sun. Then the cleanup team would drag the victim outside of the club and take off the club’s wristband to erase evidence that she was drugged while inside the club. 

"There are a lot of bathrooms inside the club, so when the VIPs smoke weed or give the women GHB… The VIP rooms have bathrooms inside, so they’d rape the women inside the bathrooms. A lot of the [VIPs] would often leave the women in the bathroom.

There was a rule. When we kicked out the victims, we took off their wristbands. That way, we can claim that this person drank somewhere else but came to the club to cause a scene.

We take off their bands while exiting the club to get rid of evidence that they were inside Burning Sun.

We leave them on the bench outside the club for them to wake up."

— Previous Employee Of Burning Sun

Source (3)

Fourth witness:

A female, Miss Lee, is also accusing Burning Sun of these behaviors. She claims to have been drugged, raped, and threatened by a business partner of Seungri. She visited Burning Sun last year on December 15 and lost consciousness after having received whisky shots from the wealthy business partner from Thailand. She has no recollection of what happened to her from that moment until she woke up at a hotel room. When waking up she was violently assaulted and raped by this man. (Graphic details have been left out from his article, but can be found in the original article). 

She was then forced to take a photo with the man, while smiling, or else he wouldn't let her leave. She complied as she was still fearing for her life after her earlier assault. After leaving the place she reported him to the police, however he was released by police as the photo apparently proved it had been consensual sex.

The woman claims that the wealthy man from Thailand was connected to Seungri, since his director from YGX, a subsidiary of YG Entertainment (run by Seungri) was with him. "The YGX employee stayed in the corner all night. Looking back, it felt like he was in charge of taking care of the people from Thailand. Somewhat of a concierge? Like that?" - Miss Lee

Fifth witness:

Another witness claims to have seen them that night with Hwang Hana and a DJ managed by Seungri.

The man have been on the local news in Thailand, denying any connections to Seungri after this issue was reported in Thailand. This man is also supposedly one of the foreign business partners who Yang Hyun Suk mediated prostitution services for.
Source (5)

Sixth witness:

Another woman have also made claims of possibly being drugged at Burning Sun. On March 28 she revealed her story to Donga Ilbo (Korean news paper). Apparently she had one glass of champagne with a chinese man on December 23 last year. After this she have no recollection of what happened until she woke up 10 am at the Gangnam Police Station. She was told that she had been arrested for assaulting a female guard at Burning Sun.

She requested a drug test from fear of having been drugged. The policemen however acted suspicious in her view and threw out the result and told her to go home. When her father contacted police for further investigations the response was that "Burning Sun is not a place for doing drugs” but also that the test results were not normal, that there was a possibility of date rape drug "but because they’re Chinese, if they go back to China we cannot find them." This woman have on February 27 filed a complaint against the 4 policemen with the Seoul Central District Court for dereliction of duty. 

Source (6)

Seventh witness:

The allegations are similar to what a writer Joo Won Kyu found out while working undercover in Gangnam's club scene. He pointed out the figures behind the clubs involved with underaged prostitutes & snuff films as "Members of the idol group S hold shares and numerous celebrities under the large entertainment company Y are participating as shareholders".

Source (7)