Mtn contracts

Good day. I had a contract with mtn, so it was coming to an end last month so i went to the store just to want advises about the closure so they said i have to make the payments of outstanding balances and call them after for the closure. I paid now I'm calling i can't found them and still there is no option to select the closure of contract. They blocked the contract simcards and now im getting emails that i have to pay for something that I'm no longer using. Mtn whats wrong with you please assist me.