My withdrawal being held

I have been playing on this site for a few months now with no problems with depositing, and I made one withdrawal of $750 with no problem.

I am now requesting a withdrawal of my winnings in the amount of $1500.

I received an e-mail saying that they require more information for verification of my account. I replied to the e-mail with the info requested and have not heard back from them so I sent a second and then a third message inquiring on the status of my withdrawal.

Not only do I not have my $1500 but I also have no access to the $500 in my account to play with.

They have blocked me from being able to log on to their site. It is as if I don't exist and my money is gone.

What recourse do I have?