CONTRACT PRICE INCREASE

I signed a 24 month contract on 1 March 2014 for R389 per month which include calls, sms's data etc. All of a sudden from January 2015 the amount that I paid has increased from R389 to R399. I contacted Cell C to see why I was billed more that the agreed amount as per the contract. I was advised that this was an increase in price for the specific contract, and that it is in the Terms and conditions that stipulates that Cell C can increase the prices when they see fit. This increase came not even a year after I signed the contract. If there are increases in January, this means that I will have a second increase in January 2016. This means there will be two increase in the 24 month contract. My previous service provider did not increase my contract price during the 24 months contract at all. I guess I will be moving back to my old service provider.