Contract Activated after whole year it been canceled for a they took back

Last year's in March 2022 I took a contract phone with MTN and within a week after I have received the phone it had some technical issues and I had to take it back to the MTN store @ Highveld Mall they took a month before I could get a proper feedback which was the "the contract is not activated that why it taking so long" and I requested that they cancel the contract since it was not active but a year later they sending statements and invoice regarding a phone that i dont have which they took back . When I go to the store they are saying the contract was activated on 30 April 2023. After I canceled it