That is strange.
I know some banks (credit card providers) blocked ALL gambling transactions, but if you've used the same card before...?
You can not withdraw to any Mastercard at most places - except at William Hills somehow..?
But usually if you can deposit by Visa you can withdraw the same way.
I would thoroughly recommend opening a Neteller account though - after the initial ball-ache of verifying your account etc. it's far easier & much less hassle!