Two days with no internet connection

I’ve upgraded from 4G to 5G biggest mistake I’ve ever done two days down the line I have no connection Rain Support keeps saying “make sure you have a 5G sim inserted” “restart router” “we’ve escalated to network division” Yet when I initially called yesterday one consultant told me she can’t find the new sim on their system. We can’t watch tv, have to buy data for social media and can’t even work from Home as I have no connection such an inconvenience. How was my 4G closed before the 5G could function properly. I’m so disappointed. Please advise when will I have connection, if I’ll even have connection…. If not then reinstate my 4G plan