Disconnecting my phone every month

December 2015 I went to MTN Kollonade to upgrade. The lady assisting me to upgrade help me to take a new phone and a Ipad on contract. Contracts was signed and I was approved for the new upgrades. My first debit order went of for the full amount of R1000 then my phone and I pad got disconnected. After calling MTN no one could assist me and I was referred to go back to Kollonade branch. The lady at Kollonade branch explained to me because my credit limit with MTN is R600 that is the reason why my phone and Ipad got disconnected but she then send a email to head office and confirm this is sorted. This month I received the same problem MTN received the full amount of R1000 but again they disconnect my phone and Ipad. This is really frustrating for me they got their money every month why must I struggle like this every month. I have my own business, my daughter use the Ipad at school and I am working on building sites from Limpopo, Witbank, Warmbaths my jobs is lined up for 2 weeks how the hell must I just leave my job and go to a branch in order for my phones to be reconect. I am fed up and for every job that I am going to loose due to MTN lack of incompetance I WILL SUE MTN.