********** telecom phone company

I was contacted 3 months ago regarding a cellphone deal which included a phone and a tablet. When it arrived, it was a different phone from what was discussed so immediately I arranged to send it back and the company said it would be collected. 3 weeks later, after multiple phone calls it was finally collected from me. Then the situation went from bad to worse. I was billed monthly with ridiculous amounts for a phone I don't have. I tried phoning about 15 times to cancel it, every time being told it is now cancelled but still being billed monthly. Every time, the new consultant would have no record of the previous conversations or even the fact that it was collected. I tried reversing the debit orders, but each time they'd change the reference number and take off more money the following month. I've seeked advice from a few MTN stores, but since Mondo mobile is an independent company, they are unable to help in any way. I don't know what to do anymore but perhaps seeking legal advise.