just checked what my mobile plan says in My BT and it now says:
### Mobile 10GB Single SIM 5G Plan
But I’m guessing I still need to contact support to get an update on the sim or new sim?
Actually. Just checked and my Iphone12 offers 5G options under mobile data and Apple seems to suggest I wouldn’t see that screen if it wasn’t activated. I recontracted a short while ago on a Black Friday deal so I am now thinking I actually am on 5G!!
Sorry to be an absolute pain but just tried the Apple suggestion of turning Airplane mode on and off and briefly saw 4G then switched to 5G.
So case closed I think.
You don't need to regrade or change contract, you just need to ring and ask for it to be enabled on your current deal.