i need some advice please

hi, i recently opened an account with titan poker, and deposited 20 pounds...... i made this up to 70 and decided to cash out....... i cashed out and had a new balance of zero..... at this point my gf asked me to close the account as she doesnt like me gambling, so i thought fair enough, and did it....... wen i chekced my bank, titan have only paid me back my 20 deposit and are refusing to give me my winnings stating this......

'John, we coordinated your concern to our Relevant Department. Based in our
procedures that they have followed in dealing with players who identified
themselves as compulsive gamblers, your poker account must be closed, your
initial deposit must be given back to you and your winnings must be voided as
if no transactions with us has transpired.'

Now this is complete rubbish, if i had lost the 20 pounds, would they have given me back? No.. of course they wouldnt.. i won the money fair and square and they are refusing to pay me........ a poker site is entitled to make money from rakes, but not from stealing peoples winnings! does anyone know what i can do other than email them...... i assume i have some rights here.... any advice would be great
thanks
john