MTN cancellation - Still being billed for cancelled contract

I cancelled my MTN contract in August 2025 ref ***. According to my telephonic conversation with the MTN agent everything was fine as it was due for cancellation in that month. I confirmed that after my final payment I would not owe any monies as I would be going on prepaid. I received an sms confirming I am on prepaid. Tell me why I am receiving sms threatening me that I am owing money and that MTN is going to block my outgoing calls. one of the sms's states payment is due 02/09/2023. I have been on MTN for many many years. Why does the left hand not know what the right hand is doing ?? do you guys even know whats going on ?? This is terribly frustrating and better not affect my credit record. I will be moving to a different service provider !!