I've just had my phone for 6 weeks no problem. But for the last 2 days I am not receiving incoming calls . My service provider are saying its a network problem. Nobody else seems to be experiencing this problem !!
I had a similar problem with my S21 Ultra. I can assure you it's not the phone's problem. Usually this happens when you switch to a new phone (mine was working fine for a few weeks and then this same problem happened). Call up your provider again and say that you're having this problem, they usually have a specialist team that resets some stuff behind the scenes. Weird that they didn't fix this the first time though 🤔
But it's their network...so if there's a problem with the network, they should be the ones to fix it. Or maybe ask them for a new sim card (with the same number), although I doubt this would fix the problem because of the aforementioned reason.