CELL C UPGRADE/CANCELLATION GONE WRONG

On 3 May I had requested for someone from Cell C to contact me as my contract had expired at the end of April. I either wanted to cancel my contract or get an upgrade. I had received an email advising that someone would b in contact within 2 days. This did not happen, and I completely forgot about it. When I received my statement from Cell C in June, I noticed that my monthly fee had doubled. I had requested for assistance via email and on 30 June I received a call advising that someone from the retentions department would contact me and advise on a refund for the additional amounts I had been charged. On July 1 I received a call from the retentions dept and was advised on a new contract which I was interested in taking out, however I required feedback on my refund before I was willing to accept this offer. The guy said he will check with management and call me back. its more than a week later and I have still not heard back from Cell C, I have sent them an email reminder yet I still wait. I received a July statement from Cell C and its evident they will be deducting the higher amount again. This is utterly ridiculous.