Poor Cell C service

I entered into an agreement with Cell C for a 50 Gig data only contract in December 2018, after eventually getting my data card 2 months later I received my 1st bill for this service this month, only to find out that they are charging me 244% more for the contract than the original signed contract. To date I have called them 2 to log an dispute, mailed them 3 times and they don't come back to me or close out the reference number and then ask me if I was happy with the service even though they did NOTHING to resolve my issue. When I get customer satisfaction surveys sent to me I mention as much and even then they don't reply. THEY ARE USELESS