BAD SERVICE FROM FNB

I had a personal loan with FNB which is settled on 14 Feb 2018 after they sent me a settlement letter. FNB took a debit order of R158.00 from my bank account at the end of Feb and I called them to find out why I was debited since I settled my account. I received an email from Nokuthula Masondo, Koketso Moloi and a few others to say my complaint will be attended but nothing was done. Now they have blacklisted me for R4400.00 which they say is the balance from the settlement I made. I am not aware of any amounts owing to FNB since my loan was settled. Nobody is assisting me in anyway the only thing they do is send me an automated email to say they will look into the matter since end of Feb 2018 to date. My name is now blacklisted for what I don't know. FNB's service have been very Horrible thus far. I am very unhappy client and want them to remove my name from ITC as I settled the account - I have proof of settlement with me.