INCORRECT BILLING AND INCONSISTENCY

On the 9th of April I purchased a data contract for R99 a month. I was told that with CELLC you pay in advance for your subscription, meaning I had already paid for April, and that this data contract would start in May. At the end of April I was debited R279, and at the end of May R171.59. I emailed customer service on Monday, and with no response, emailed today again (Wed03/06) and after still no response I called in, explained my situation, only to have a call centre agent shout at me and tell me all debits are accurate and legit, I requested to hear the call and was told long stories, and put on hold. I eventually dropped the call as I cannot sit on the phone all my life she didn't even bother to call me back. I managed to find the email address of the person who contacted me on the 9th of April, and asked them to assist, and I have it on email that at the End of April I was supposed to be debited R99 going forward. I feel that CELLC is *****ing my money and that when I call to get assistance I get shouted at which is totally unacceptable, PLEASE REIMBURSE MY MONEY AND SORT THIS OUT OR CANCEL MY CONTRACT! Thank you