FNB CREDIT CARD DECIDES TO TAKE MY MONEY WEEK AFTER WEEK!!

the problem started when i started paying for my flight tickets,i had a credit limit of R17700, there i moved only R11700 to my straight account,and i also tranfered R8000 to my credit card so that i can only use R3116 form the credit card the rest i used my own money because in total the plain tickets were R11116.

This means that from the Credit card straight limit i only used R3116 and i was left with R8584(CREDIT)

The total that i was suppose to be owning is R3116+R4768(what i owed before the purchases)=R7885, then i decided to pay R1500 the next day after i made the tickets purchase, then FNB without my KNOWLEDGE OR WARNING THEY DECIDED TO TAKE R1630. when i call to ask what is happening and they told me that my credit is over limit, on Friday 02/02/18 i visited the branch to query this and the lady over the phone told me that its FNB system that did this(decreased the limit), the other one told me that its me who did it and i never called the bank on the 27th feb 2018 because it was on weekend even. The consultant that told me that its their system told me that she will create a CASE on my account and someone will get back to me within 24hour, NO ONE ever DID!! until Monday when another amount of R1080 was taken again without a notice or warning. when i called no one was able to help me or even give me phone records were i agreed to an overall credit decrease, there was no notification that came to me as well about this decrease if really it was authenticated by me. i HAVE BEEN PAYING MY CREDIT CARD REGULARLY NEVER EVEN MISSED A PAYMENT BUT NOW FNB IS TREATING ME LIKE I AM CRAZY. I WANT MY MONEY BACK AND MY CREDIT BACK TO NORMAL, EVEN WHAT I AM OWNING PLEASE, I DON'T WANT TO THINK ABOUT MOVING MY ACCOUNT ALL TOGETHER!!!