£12,000 winnings denied

Hi, i set up an account with Jackpotjoy and deposited £25 to the account. I used my sons card as I didn't have mine with me, I of course had his permission to do so. I somehow managed to win £12,000 which I was overjoyed about. I contacted the company to withdraw these funds, and they advised that the funds would have to go back to the original card on file for player safety, this was fine with me and my son and we told them to go ahead.

They then cancelled the withdrawal and asked for verification. They requested ID, a letter with my address, and a picture of the bank card used to make the initial deposit of £25. I went ahead and provided them with all of this and the withdrawal was once again processed. The next day I had an email to tell me the withdrawal had been cancelled. So I logged into my account to find out why, to which I was told the account had been closed and I need to call customer support.

I called up and was advised that players are not allowed to use someone else's card and that this was fraudulent, and because of that, my winnings had been voided and the account was closed. After carefully reading their T&Cs, it does NOT say that you cant use a third-party's card, in fact the only mentioning around card/registration is this:

4.1.3.

have a valid bank account, credit or debit card or alternative payment method that is approved by us that is registered to an address in a territory from which we accept users from time to time;

i do have a valid bank card, i do have a valid bank account, and they are registered to an address in a territory that jackpotjoy accepts. Surely this is completely illegal? When I initially entered the card details, I entered my son's name as the cardholder, and MY name for the account! I have in no way acted in a deceitful manner or tried to trick anyone. I had permission to use this card and I want my winnings.