***** case closed with answers

I’ve been struggling to get assistance, on the 03rd September I made a Sim Swop of the number ******9149, however the sim card was unused and its still sealed from the day , I got it however In November I discovered my line was still being used without my consent, and no one is providing feedback as to how was it used and new sim being made without my permission, whenever I call the contact center. I’m being told the case is closed yet my questions are still unanswered. And I’m being billed for transactions which I didn’t do. Please assist