MTN Still Billing Me and wont refund after cancel

In August last year I emailed MTN to ask them to please change my sim package to prepaid when the contract expires the next month (September) I specifically did it a month before so that I could spare myself the ******* service you constantly give out when people want to cancel. I spoke to a gentleman who asked me if I would like to change my contract to prepaid or to cancel it straight.. I said I want to keep it as prepaid as I use the sim but want to control my own airtime spending and not have monthly data. This I sent to customer care as per his instruction.<br> <br> Now, 4 months down the line and you people are still billing me!!! I was told an investigation would be done but that I must send proof that I requested the change over to prepaid, which I sent. Now you have changed it over but I still got billed this month for your package I don't want AND I have not been reimbursed for the months you've ****** from me.<br> <br> I want a call from a manager, today. I want to deal with 1 person, not 5. I want a request for reimbur*****t opened on your side. My request was sent through to you guys twice and there is no excuse for not doing as I asked. And ignoring my request still makes you liable.