Payment for purchase on Ebay

Question

Payment for a purchase I made on ebay was debited from my bank account instead of being made from my credit card. Can this transaction be corrected & why did it happen? I have 2 different credit cards on my account & thought that's what is used. I thought the bank account was a back up. I don't want the sale stopped, I just wanted the money to come from a different place. If it can't be shifted please advise me how to prevent this in the future. Apparently I don't fully know how to make sure where the payments are coming from. Thanks