pathetic service

I experience bad service from MBD Attorneys. I did an upgrade to Samsung Tab 3 lite @ R159 per month top up amounting to R3 818 whole contract term. MTN closed that contract handed over to MBD attorneys. MBD attorneys gave me ridiculous bill of R 18 389.37. I told MTN and MBD that BEFORE I made my upgrade there was an ********** contract upgrade on my MTN account. I opened identity ***** case with SAPS, case number 248/4/2016. MTN ***** department gave me this reference REQ ********** . From January 2017 until 28 September 2017 I paid R500 monthly towards the upgrade I made thou it was closed by MTN. I paid R 5 000 to date. MBD can not solve this case telling me they wait for MTN to respond. My case at MBD is handled by ********** that person never responded to my emails. they give pathetic service, I do not owe MTN anymore I do not know why cant they solve this case and remove me out of legal.