Sim swap - Service Provider Not Helping

I had a problem with my sim card, then went to MTN to report it. MTN then realised that I had a contract with JET Store which is dealing with RMCS. I went to Jet and they contacted RMCS for me where I was given an account to pay R140.00 into their Standard Bank Account which I did, and they delivered a sim card to me on Tuesday the 07 July 2015. I then called them back on receipt of the sim card so that they activate but they promised to call me back in order to sort out my issue. They never did and I have to date called them about three times but they are turning me into a fool because they keep making empty promises but not deliver. This entire thing is inconveniencing me because I have no other mobile to use. I had actually cancelled my contract with this Service Provider sometimes last year although Jet said it was on the 07 January 2015, and Jet called them to move it to prepaid but it was never done. I WANT THIS TO BE A PREPAID SIM CARD GOING FORWARD, AND BE UNDER MTN, NOT RMCS..