Debt review overdraft payment

I have been under debt counselling since May 2014 and was supposed to finish in March 2019 after 5 years. Last year January I found out that my interest rate on my overdraft was never adjusted as per the proposal sent by my debt counsellor. I logged a complaint with my debt counsellor and they started the process of getting FNB to check and back date interest on my 2 x credit cards and overdraft. The credit cards were recalculated and credits was paid to accounts within 2 months. The problem was with the overdraft. FNB kept on saying that they had a back log with debt review cases and that it was with the product house for reveiw. The case dragged on for almost 12 months and finally they said that the account could not be restructured. I now have to pay of +-R29 000 after I've already paid the same amount over 5 year, wich means in the end I paid R50 000 for an overdraft of R23000. All I want to know is when FNB was notified that I was under debt reveiw, why didn't they seperate the overdraft for payoff like they did with the credit cards. Why was the cheque account kept active and accumulated 5 years account charges while I was only supposed to pay off the overdraft and not using the check account. I have been an client of FNB for more than 15 years of wich I worked for FNB 8 years, but I will definitely be moving to another bank.