Disgusting bad bad service actually no service

I have had problems with my signal for the last 3 weeks and have lodged numerous complaints with MTN Secunda Mall and Head Office, up to now nothing has happened and I am still without signal or connection. They first told me there is something wrong with my phone and I need to upgrade, which seemed not to be the problem since I placed the simcard in another phone and the problem were the same. They then apparently reset the simcard from their side for which I never received the settings and when asked for it again, was refused that they will send again. Then I was told to do a simswop and upon visiting the store on Sunday to do a sim swop I was told that it would not work and they will contact the call centre on Monday. The lady called me back after I had to call her again and said head office said my complaint is in a queue and I have to wait my turn and she will follow up. Three days later no call back only to find out this morning she is off and will look at my complaint tomorrow - I run a business and have been without my phone for the last 4 weeks because of their incompetency . I really consider to cancel my contract since I receive no positive feedback or assistance. I also do not pay the amount my contract was for initially and much more and for that they also do not have a resolution and give me all funny answers.