Hi @Purple_Worzel welcome to the community! Thank you for posting.
Sorry to hear of your difficulties accessing 5G on your new handset. Having had a look for you your current handset it not one of the devices listed that we support 5G with. (You can see the list of compatible devices and read more about 5G here.)
However as you have already mentioned, we are working on adding more devices to our 5G network all the time - hopefully this will include yours soon!
Apologies for the poor experience and any inconvenience caused.
Do let us know if there is anything further we can do to help!
All the best.
Molly