I had the same issue which I think is BS! Hotel has +550 rooms, so there is no way all standard rooms are sold out months in advance. Plenty of standard rooms for sale.

1st night only room available is family room for 55K. Other 2 nights are 44K each.

I went ahead and booked 3 nights this way since I had no choice.

At check in I was told I was upgraded to a 2 room suite on business floor #24 , and I asked to stay all 3 nights in the room and they accepted. So this actually benefited me.