MTN contracts and billing

My contract came to an end July last year 2023. I have repeatedly asked for the cancellation of the SIMS as per set guidelines from MTN and to date they keep on billing against the SIMS and request payments. As per directive, i had to mail the following services , customer care, CIM_Legal and retentions at MTN and not one of these departments have confirmed yet they add to the bill. If not resolved then i am going to the media over this debacle. MTN must be one of the poorest institutions around accounts.