Vodacom Data

Good day Peter I recently received a bill from Vodacom of R 4 290.53 I called Vodacom to report and dispute this bill because I've had this contract for almost 2 years and have never exceeded my maximum use of 500 MB which equating to R115 monthly charge. I have also been soft-locked every time I reached this amount now all of a sudden they tell me that I am now on an open line and somehow I managed to use data worth this amount. Even if that was the case, I only use this table for Whatsup and facebook, how much whatsupping and facebooking do I need to do for my bill to be R4 200 in the space of a month???? I called Vodacom on Saturday (10th) to report this issue and they responded with a lousy statement via sms on the 12th stating that this charge is correct because I was using google https and also told me that as a "gesture of goodwill" they will credit my account with R2 878.35. I then called them again to let them know that I do not want their "gesture of goodwill" all I want for them is to do their job and check who used this data that I know I did not use! they have since not sms'd me nor called me and this matter remains unresolved. I would like to request Vodacom investigate this issue immediately and provide me with a correct bill. If they continue to insist that I used this data I want them to provide me with a list of all the so called google https sites that I accessed that led to this bill. Once this matter is resolved I would like Vodacom to cancel my contract please. Regards Angel