This is one of the 'legal' threads that VWM loves so much!
IF you can demonstrate to the CC company that you haven't received the goods/services you were legally entitled to when making the transaction, you can use Section 75 to get a refund if full. They have to give you a refund by law. So the CC company needs to be informed of which rules the casino broke - in this case taking your CC deposits for void bets (under UKGC rules) therefore not providing you with the real-money betting you were purchasing. To avoid this, an accredited site would usually automatically refund the deposits and void winnings if your OP is 100% accurate.
Chargebacks not only cost casinos deposits, but they are a black mark against them on their CC processor and too many can cause them much hassle and charges levied by their processors. This is why you should only do this as an absolute last resort if all else fails, because you could find that shared data comes back to bite your a$$ in future, when a casino shuts your account with winnings in and refunds deposits.
So, simply point out that as the bets you purchased were void, your deposits were null and should be refunded. Ask the casino and/or the rep here.
If this fails, ask Max to do the above via a PAB. It should be quite straightforward if this thread is kosher.
If you have tried to resolve as above and all has failed, then as long as it's within 180 days of the deposit(s) then ask the CC company. But this is an absolute last resort, and a casino like
Unibet/Maria would be unlikely to let it get that far. Remember fraudulent chargebackers (sounds like an NFL team lol) are the dog turd of the sidewalk and have no place in gambling for very good reasons.