MTN Incompetance

What frustrates me the most is when they call you with a new offer. You accept the terms and the new reduced rate, then you get the bill and the rate is still the same ! I then went into a local MTN office, as trying to speak to someone is impossible. I was then told that that was the final bill, and the new rate would reflect on the next account. The next one was exactly the same, so I went into their branch in Somerset West Mall. The chap that helped me looked up the details and said to me that he has fixed it now but the rate would be different to what the òriginal lady gave me. I said ok but just fix it. He then proceeded to tell me that I must not deal with their call centre as they tell lies !? The 3rd bill which was end of May was exactly the same - No change. I have given them an altematum now - fix and credit, or cancel the agreement.