Vodacom *****ing data!

I have a 2GB internet bundle per month at home. I rarely use this up as I mostly use it for internet banking. This month, the 2GB was depleted by the 24th, which is possible. I then bought another 1GB of date on the 24th only to find out it is depleted on the 26th!!!! I phoned Vodacom yesterday and they told me the data was used between 12 and 4am!!!! I am not even awake at that time and my computer is not connected to the internet during the night! The person I spoke to at the call center said they would send me a detailed report as to what used the date, but I still have not received this. I want my data back Vodacom! I did not use it! Check my internet history! I don't ever download things or surf the net for hours on end! GIVE ME BACK MY DATA!