Poor & dissapointing service

My phone contract with MTN ended January 2022, I called mtn for full and final settlements twice and I settled the account, now in April they keep trying to debit my account and I called again and the agent advised my number is back to prepaid she doesn't know what the bill is about, they still trying to debit even now and going as far as threatening to block my number and suspend my services. @mtnsa this is disgusting for such a big company. Please fix this immediately.