Two scenario
- Either you still have some balance left from the bonus (but these one should be not, cause based rules the balance should be forfeits)
- Bugs

Can't do anythings from user side, the things you are doing was correct. Contacting support, based the explanation on last statement in the bonus page information. BTW have you tried with other crypto ? these bonus tied to BTC right ?

It's other crypto are not being using for the bonus also effecting your withdraw tx ?