unfairly billed

I have a data contract with Telkom wich consists of 5GB anytime and 10GB night surfer. I took the contract somewhere in November if Im not mistaken. Contract was taken at Kyalami corner. Everything was fine for the for the November Pro rata and December. But in January my 5GB only lasted for 2 days then I was out of Bundle wich raised concerns. I then went to Telkom Kyalami corner for explanations. Then they looked confused as well and called the IT guy to check it out. The guy then said there is a 3GB that went off all at once but he cant explain how it happened but he will send the incident to the department that deals with such quires , they then told me I will receive a Ref number shortly once the incident has been loaded but I knew once I leave that store nothing will happen. Even the call centre provides pathetic services even a ****a shop does way much better. I want to be reimbursed my data because this is day light ******* seriously and a full explanation on hos a 5GB can last only 3 days.