Mweb usage not matching up and I as the client is wrong in their eyes

I recently moved from Telkom to Mweb on 01/09/2017 for a 20mbps UNCAPPED internet package to save some costs on internet fees. However today 15/09/2017 I received a message from Mweb that I have used up my fair usage data (which is suppose to be 500Gb) and am now being throttled (at 455Gb according to mweb and their system). I thought to myself that this cant be right and have then logged onto my mweb account page to verify my usage and it shows there that I have only used 258.19Gb out of the 500Gb that I am suppose to get before I get throttled. I then phoned customer care at Mweb and they are convinced that I have used the 455Gb and that I cannot do anything else to this matter. I will now have to wait until 01/10/2017 before I can get unthrottled and I know for a fact that I have not used all my cap and they then expect you to pay full price and giving me the use of half a product.