Spin and win

I joined spin and win and deposited £50 and got a matched £50, played the games for about a hour and was up to 700 pound, went to withdraw and it said cancel the £50 bonus remaining balance £650 so I did this and it's took the whole balance, I have phoned them and because I won with my bonus balance that's why it has done this, the site won't put the money back on and let me play through the wagering requirements which turns out I had played through 73% of, what is the next step to this do I just lose the money or is there somebody I could contact to help me resolve the matter help plz