Terrible service and policy

FNB Had taken out the minimum payment due on my credit card automatically on the 31st of May AFTER I had paid the full amount due on the 29th of May. I then chatted to Mampholo who told me that it is FNB policy to do that (but this was the first time it happened to me and I signed no document of that) and that I had to pay the full amount due 3 working days before the due date for FNB not to take the minimum amount due on my credit card from my cheque account. According to my understanding from my statement, the credit card amount was due on 1 June and I paid the amount on 29 May, does this not qualify as 3 working days (which I also find very unreasonable as there should be efficiency with regard to this on the part of the bank. Also I had previously paid my credit a day before due date and no minimum amount was automatically taken out). I always budget myself on a monthly basis and as soon as my salary is received I pay the full amount due on my credit card, I leave the other funds in my cheque account to settle my other monthly expenses and debit orders and when FNB took out these funds it left me with a problem and resulted in some complications for me. I view this as a breach of my trust and the service I received was very very poor, i am currently looking into services by other banks and considering a change as I do not want a repeat of this matter.