Worst bank ever! Robbing people.

My ID number is ***. On July 16, I made an online purchase of R3600 and some rands using my fnb credit card, which I cancelled in few days, and was refunded an amount of R3300 and some rands. Instead of the amount owing to decrease after receiving the refund it increased with R3300 and some rands and later decreased to the amount it was before the refund, as if no money came into the account. The amount of R3300 something is still missing, and fnb is unable to trace its whereabouts, apparently because I have been shifting funds from my budget to straight after that transaction. FNB is failing to see that the reason I shifted funds was because the money was already missing, leaving me with no options but to use shift funds from my budget. I want FNB to credit my account with the same amount that is missing, because I am not prepared to pay for something I did not use, and which is missing in their system. From now I will be working on settling my credit card with this bank, because they are robbing clients, and move to another bank, and I suggest, if you dont have it with FNB, get it from another bank.