Being ****** and charged for data usage that I haven't even used

I signed up for a CellC laptop contract with Altech in June 2014 and have recently been transferred over to Glocell. The contract was an open line but I switched over to a top up plan on the 29/02/2016 due to extra charges being incurred. From a contract that costs R229.00, I have been billed R1619.00 at the end of April 2016. I queried this with GloCell on the 15/02/16 and have been advised that the query has been lodged with CellC. I am still awaiting feedback to date. According to GloCEll nothing can be done on their side as they are awaiting a response from CellC. I have been wrongly billed and this does not seem like it is the first time. According to the itemised billing that I have received, there is a record of me being on the internet from the the 01/03/16 at 18:19pm until 03/03/16 at 17:11pm with no break inbetween and on the 06/03/2016 at 21:38pm I used 1,024 data and then again at the exact same time I used 1,369,502,720 data. This is complete nonsense. I have not used the internet during this time. Furthermore, I am a working class person and do not have the time to sit on the internet for a period of over 3 days without getting up. I did not use this data. Also, after switching over to the top up contract I was unable to connect to the internet. How could I have used up that data if the device did not allow me to connect to the internet? Finally when it did connect at one stage, it allowed me a few minutes then I got a message to say Data depleted. I want an answer. This isnt the first time. During the first month of my contract I was also billed a ridiculous amount and when I asked for proof no one got back to me. I want my money back. I have other committments. I can't be paying for a service that I did not use. CellC should at least have the decency to get back to me.