FNB is the most *********** bank ever

I had a loan with FNB in 2010 which was paid up before the term was over. i am up till today still told by FNB every 3 - 4 months that there is an amount that i owe on this, its either an error by their staff. or an error on the system. no apperently an amount of R200 was written off by them. and yet i must keep on paying and paying towards a closed off loan. this is not on. and to add they then mark me as a risk on their system and prevent me from collecting Ebucks and other services. all this because FNB doesnt seem to have even 1 competent staff in their whole company.