Incorrect Billing

So i have been with Telkom LTE for 4 years and this is my second LTE contract with them. First one was 3 years and never had any issues, my current contract is 24 months and i am 15 months in. Never had any issues with Telkom until i received my invoice yesterday. I pay R707.50 pm every month for the last 15 months and when i get cut off i cannot use the internet as this was the agreement. To my surprise yesterday fro the first time ever i have an additional cost on top of the R707.50 i pay. The invoice states i asked for an additional 101 G of internet at R399.19. So what concerns me is I never gave permission for any additional data to be used once my bundle is depleted and secondly and i confirmed this again yesterday evening i have never seen this so called 101g extra data that I "requested" according to Telkom. Now i am almost a 100% confident Telkom will do nothing and i will end up paying this R399 ghostly additional cost like i am almost 100% sure other people have also done in the past. but luckily i have 4 contracts with Telkom between myself and my partner and guess what they all come to an end this year (2018). I will rather move to another provider because at least when they charge me for an additional cost I am sure I will at least be able to use that additional cost.

So Telkom the ball is in your court now, let see what excuses you come up with (If you even have the decency to respond on this review) to force me to pay that extra R399.12 that was not in my initial contract agreement.

Good Day

Nino