MTN Contracts

I had a contract with MTNSA and after if ended I called them to notify them that I need a cancelation on the other device as I upgraded my package on one device of mine. I noticed them last month on the 24th July 2021 when my contract lapsed then today I saw them still giving me data on the very same device that I canceled the contract on and when I made a call to an agent I was told they didn't cancel my contract, it is still activated ?? The agent then transferred me to the contract Champion and I was on hold for 45 min without any help

I regret why did I ever take a contract with MTN, I should have sticked with other service providers who do t have his kinder behavior

It's really ****ing me off