Disappointed client unable to upgrade

I have been trying to upgrade since my contract expired on 23 June 2019. I have been to two stores: Potchefstroom (twice) who informed me that there is some ********** account linked to my name that is in arrears and now blocking my upgrade. After visiting the Clearwater Mall store (where I have always received excellent service), I was informed that the manager advised me to pay the outstanding amount on the ********** account!!! That is now after two weeks holding for "legal" for hours and get cut-off every time. How's that for service? So, now I have sent numerous e-mails to MTN and their contractor handling the upgrades - yes, I had to write an affidavit stating the ********** account does not belong to me. This was done on 23 July 2019, up to today I have not received any update from Phelo or her supervisor Mosa. I am not paying my account - the difference between keeping me on the current contract and the one I want to upgrade to is R1 000 - very convenient for MTN to drag this out as long as they can! What a disgrace....not a single competent person in employment?