Ubisoft charged me twice for the same game, refused to refund accordingly

I had bought a game on the Ubisoft launcher, it was reduced to £10 from £25, so i purchased the game for £10 from my debit card, moments later they charged my card again for £25, the full price of the game.

The games were the same edition, same copy, exact same product but it showed I had 2 on my order history. I put a refund request in for the more expensive one, but got declined almost instantly. Sent a ticket to support but after a few hours I ended up playing the game, 3 days later support answered, saying they refunded the £10 version.

Questioned this and told them I requested that the incorrect charge for the £25 version be reversed, but they refused, stating that I had played the game more than X hours

They refuse to accept its clearly an issue with their launcher, as the game shouldnt have even been able to be purchased for £25 at the time, and I wouldnt have paid that much in the first place.

I told them I would do a chargeback with the bank, but they threatened that they would ban my account if I did that, meaning id lose access to several hundred £ worth of games

Is there any legal jargon I can throw at them for them to rectify this? I even said I would accept the difference in store credit even though it was their fault

Can they actually ban my account for issuing a chargeback? The initial refund request was made before I even opened the game, in line with their T&C, but seemingly auto rejected for no reason, then they took so long to reply to the ticket that Id gone over the timeframe for a refund.