Failure to close credit card account as requested in March and continuing to charge monthly fees.

I have had a cricket card with FNB for over 10 years. I always settle in full every month. I no longer need this card and have been trying to cancel the card since March this year (it is now mid June). I have telephoned multiple times, send numerous emails with the correct cancelation forms and been into the Longbeach branch. I have numerous reference numbers but the account continues to remain open and monthly charges being levied. I have paid these charges and repeatedly requested the account to be closed. My accounts are all now with NEDBANK and I was able to close an ABSA credit card telephonically today with a single phone call. How can FNB make it neigh on impossible to close an account, even within a branch? David Clarke