Unbelieve customer service developments with my FNB Premier credit card.

For many years I had not been paying credit card fees on my FNB Premier card in association with my Premier Select current account and being over 70. Suddenly in Dec, I was charged credit card fees. After complaining, these were reversed. In January the charges came back. After 4 attempts at complaining, I am finally being told that I should have been paying fees all along, but that it had not been done due to a system error!! Apart from not understanding any of this, the fact that I am being suddenly charged something that I had not been charged for years surely should be something that a bank agent should have called and discussed with me. Absolutely disgusting service. Anyway, I will not just take this without getting a proper explanation, and/or remedial action and apology.