OVER BILLED

I have a contract with vodacom with a data bundle of 1.2 gb, I use on an average of between 17 and 39 mb and on the occasion 50 to 80mb, on the 31/08/2015 all of a sudden I anm billed for 711.31mb = R622-11, I am not a *****e to use data on the last day of the month when I know I do not have (I check daily on the balance of my data) I call the help desk 082 111 on the 2nd to log a query receive a sms that it is under investigation I have subsquently called another 4 times speaking to Refiloe (Who would esculate it) no response, I call Zandie who promises to take it up with her Manager Brendon to esculate and would have a final answer today 22/10/2015 nothing. I was originally told a query take 7 working days we are now 20 days later, I now call and speak to Brendan he can only esculate it again and I have to wait another 24 to 48 hours sorry but he cannot give me answers can also not put me through to anyone who can and can also not give me any other contact details for anyone else, VODACOM IS QUICK TO TAKE YOUR MONEY BUT WHEN THERE IS A QUERY FORGET IT, another person I know uses 109-00 per month last month billed for 549-00 KEEP A EYE ON VODACOM THEY ARE RIPPING US OFF