I remember oxapay from this thread, see: oxapay scam payment gateway

OOP basically had an issue with AML policies as well with oxapay but was later resolved. Biggest reason I think it was resolved though is because OOP made some noise in many places so company had to damage control.

BTW, so you haven't withdrawn your fund yet, correct? Perhaps try following OOP's tracks and see where that take you.

TBH, with processing huge amounts, I'd err on the side of caution and pick a more reputable provider even with the caveats.