HUGE MTN DISAPPOINTMENT!!!

I was contacted by MTN offering a new contract on June 28, 2018. The cell phones were delivered to me and as I was not happy with the contract, I cancelled with Buymondo, affiliated to MTN via cell phone and e-mail!!! I have made numerous calls to MTN and Buymonbo with no results whatsoever!!! It cost me R295. to send the package back to MTN via Fast Mail! In the mean time MTN has been deducting monies from my account non stop and *****ing my money, which I cannot afford as I am a pensioner and don't receive a monthly pension!!! My normal subscription is R140. & they have been deducting excess fees since July 2018!!! By now MTN owes me R1076.00. I am a very unhappy, and disappointed client!!! After how many phone calls and emails and wasted time I spent to sort this mess out, I just get absolutely no response from MTN and I am beyond angry and fedup!!! Please help me sort out this mess and I desperately need my excess monies refunded to me a.s.a.p. Thank you Kind regards Mrs Lindy Crofts