These requests are just ridiculous. They will just milk this and reject everything forever. 500k is a huge sum and after already paying out a lot they suddenly want to know where the money is coming from. Sounds pretty shady to me.
I wish you could get your money but dealing with people like this I have my doubts.

They basically admit you did nothing wrong, no violation of TOS. Still they refuse to pay, what a joke!

Maybe a flag for duelbits is in place I think. Not paying 500k is just too much.

Also, time for a new place to play at.