Fixed LTE

I'm on the Fixed LTE package, was initially told that the Sim would work in my LTE compatable Huawei mate 20 device. After 10 months of working, it just stopped working last week, in the 27 September. I've been battling ever since. The Sim card would not read in my router or phone, just says "insert sim" I was now debited R319 for data which I don't even have access too. I've got a reference number that's been so called escalated to the LTE department, but I'm yet to have feedback. I've even made a new request that they just refund me my R319 as I'm not interested.