Got the phone back yesterday. They have unrooted the phone but still have no 4G. There was no note saying what they have done, or if there was a fault with the phone which I find quite strange. Checking the phone again it is a HTC One 801s 64GB and I think it will be on the 1800MHz band which is probably why the Tesco app states I do not have a 4G phone.
I take it this will be a hardware issue and there is nothing I can do unless I can get a network provider who uses the 1800MHz band for 4G? Is there anyway I can check what frequency the LTE is on the actual phone?