If you don't open anything, you can sue directly if you obviously circle money. If it's really a decoration and there are still a few documents missing, you can take the opportunity to force the gym to extend your card for a month or two.

If you have a contract.

Don't think about returning the card. Now people have some problems, even if they have problems, they have to return their cards. Which one will be returned? What business can the boss do if he can't stand you?