Double standards

I had a contract which ended on 30th OCTOBER 2020. A MONTH before then end date I send MTN an email telling them I would like my contract to be stopped at end date. I was sent an email back to say I need to cancel it telephonic ally. I did the necessary ref no I-*** and on one other occasion. Now when you phone they ask you security questions in order to help you. I was assured the contract would be cancelled. I also had a credit balance with them. Some time after that I was sent an email asking me to verify the security questions via email so they can assist me. What double standards. Now In January I owe them as the contract was never cancelled. I sent them emails to query but no answer back as yet. So much for being a loyal customer since 1998.