Casino 770 - Can't get my winnings

this is my first time on the website and you gave me £25 bonus and i won £600. so i spoke to live chat and asked them how to withdraw my winnings and he said all i had to do was deposit £30 and id be able to withdraw my winnings.So i deposited £30 and typed all my bank details in and every time i pressed withdraw the page went blank. i spoke to live chat again and he told me to go to my settings and delete the cookies on my laptop so i did. i tried to withdraw again at least 5 times and still the page went blank and would not let me withdraw.And all of a sudden i get a phone call telling me i cant withdraw unless i email them my birth certificate and my bank card.Why is one person telling me one thing and then i get the phone call telling me somthing else.i skint myself out to pay the £30 expecting to be £600 better off for my children so i want to know what to do i cant belive how stressed out this has made me your meant to have a bit of fun then it turns out to be a disaster.