OVERCHARED AGAIN

The query is on my Data Account with the above cellphone number. This plan is capped at 2Gb and every single month it soft locks between the 27th and 29th, and this I expect. It then unlocks on the 1st of the month again. This month (and while the system is telling me I still have 1.31Gb of data remaining), my account is R 3,500-00 for that alone, when it is supposed to be around R 250-00. So, I am not sure how this amount got to be THAT much as Vodacom's system was suppose to soft lock it at 2Gb as per normal, which clearly did not happen. Also, I only have my cellphone which I use on this data line (which is in a Wi-Fi router at home) and I use Facebook and WhatsApp, which certainly cannot use data of this amount. I further have 2 Wi-Fi routers at home so the data usage is shared between the 2 of them. After this happened before, I also made 100% sure that my phone updates nothing without asking me and all my phone updates are done at the office, on an uncapped line.