MTN Existing Contract Modification

I am currently an MTN client I have a cell phone contact since 1997 (26 years). I have never missed a payment. I am currently under debit review for 9 years and have always received an upgrade whilst under debit review. The last upgrade I had the contract duration was for 36 months and with the result my contract limit decreased. I am now allegeable for an upgrade however due the low contract that I currently on MTN refuses to modify the existing contract by the value of R300 in order to continue giving them business for another 24 / 36 months reason being I am debit review. MTN has never informed me that if I do not increase the contract limit, I will not qualify for a new device NO communication whatsoever from their side. MTN does not support small contracts it means nothing to them to lose a client for 26 years. There has been absolutely new support from the call centers or in the store I have been to MTN Trade Route Lenasia, I have emailed the customer support I have emailed the customer compliance departments and have not received any kind of CUSTOMER SUPPORT from MTN I can provide you with reference numbers of emails and itemize call listing that I have made to MTN. This is very disappointing service more so for being a loyal client to MTN for 26 years. DISGUSTING SERVICE!!!