incorrect billing and being locked

my two data contracts were moved to mtn from Nashua. since then every month I am being soft locked. my contract at Nashua had a condition that I can only exceed my contract with R 5. now this condition at mtn does not apply without them informing me of the change. I never agreed to the change. <br> my router broke I took it in for repairs still under warranty at the same time my laptop got ******. after I received the router back my next invoice has jumped from R 228 to over R 2 000, it looks like they have decided to add data charges that you cannot dispute to cover the cost of replacing the faulty router. They never app**** the soft lock criteria which I have also requested every month since moving over to mtn and despite it reflecting on their system if they access my account. <br> now I am being referred from one store to the next. I have been to Menlyn, two store in Brooklyn and one in Atterbury they still cant help me. not even the call centre are helping. I phoned mtn head office and still no joy yet I have to pay every month and still being locked. <br> <br> I want to have my contracts cancelled with immediate effect this is not what I agreed to with Nashua.