Incorrectly Billed

I bought 1GIG NITE data 3 times. When buying using USSD the amount states R12.5 but upon receiving my statement i was surprised to have been billed R49 for each 1Gig Nite data bought. A logged a query on the 14th Jan 2016 as i bought the data on the impression that i'll be paying R12.5 per 1gig of nite data, this is the reference number ***. I was told that i'll receive a follow up call within 48 hours and no call received to date. I even followed up by phoning call centre and was told in due cause i'll receive the call and still nothing. On the 25th Jan i was then debited for the amount of R517.96 which includes the incorrect billing. What must happen for this to be fixed? Why does one have to escalate things to this platform before receiving the service we deserve. You are quick to take your money but very poor service when it comes to resolving queries.