Dispute over data usage

I have been with telkom mobile since August 2011 & I have never had an issue until 1st of December 2015. <br> <br> On 02/12/2015 I woke up to the discovery I have mysteriously used up 6.5 GB of data in one day! This is a scientific mystery as I have NEVER EVER used up that much data in one day. My data sim is always in my huawei mobile wifi modem which is linked to my phone which is on 24/7. <br> Upon discovery, I immediately phoned telkom to dispute the usage. I spoke to a Nontbeko who could only tell me that my data was \ON"from around 10am until midnight that day. I explained to her my data is on 24 hours as the sim is kept in the wifi modem"