Useless money hungry!

Cell c this is ridiculous, every time I update my Samsung a31 , my sim card stops working completely! This is the second time , the first time I had to do a sim swop which was a month ago! Now it happened again and cell c refuses to do a sim swap and says I need to wait 3 months because it's too soon. Now you tell me, why is this my problem? Why must I be without my phone for 3 months and be expected to pay for my contract? This is beyond me! Sort this out now!!!!! ***