FNB changed my account stutas without my permissio

Two week ago I have lodged a query on my accounts ,because the bank charges I was charged were too high, FNB conducted the investigation on my accounts and the results was that, my accounts was charged without my permission, therefore FNB is not able to reversed all the amount billed on my account, they have decided to recalculate all bank charges and indicated that they will take total amount charges for the whole period divided by the number of month where my account was changed incorrectly of which I still don't understand the formula which was used by FNB. According to my understanding is that if FNB agree that they have made mistake on my account, they should reverse all charges which I have been charged during the entire period. Am definitely quite sure that what ever happened to my account is happening to a lot of FNB customers in South Africa and the are not aware.But if I take the matter up and to the public we will see the miracles. I am humbling requesting FNB to attend to my matter urgently before I do something that will effect the reputation of the company.