Contract upgrade nightmare

Why my contract was not upgraded on the day 19 July 2015 to top up R110 for R219 and only on 10th August? 19 July upgraded and changed the package to top up contract. 3 August I concerned that I do not run out of airtime queried at the store and to be told to upgrade since my contract is due for renewal. 3 August bill is R1200 I reminded that I had already done so a few weeks ago. I am told it will be investigated with HO and feedback will be communicated. 5 August I write a follow up e-mail & MTN reacted and told me again that it will be investigated. Wrote another e-mail on 10 August receive an e-mail stating that I had successfully upgraded. Write a follow up e-mail, 11 August, receive another call reacting to my e-mail and assuring me that they are still looking into the matter. 15 August 2015 called 808 discover that no call was logged on the system, bill is now over R1300. I changed that package to control my spending. MTN please advise me when the bill will be reversed, its not my fault that it was not done on the day I signed. FRUSTRATED PLEASE HELP, 1ST IT WAS ***** OF MY DATA ACC IN MAY NOW THIS. STILL WITHIN A 7 DAY COOLING OFF FOR THE CONTRACT, MAYBE I CANCELL