Transaction Banked 12 days later from my available balance

I made a payment with my FNB card at an establishment in my neighbourhood for R1500 and it went through and was successful, but only yesterday 12 days later i see the money being taken from my account, when i call the bank they tell me that this was only banked then. How does this make sense?I want that money reversed into my account, its shocking how i am inconvenienced for your delays. I need my money back in my account.