Signal

LeeTayl_2191549 Here's the thing with mobile networks - it's a lottery in terms of which one will be the "best" for your location(s) etc because one network that is superb in Area 1 is probably not so good in Area 2. Striking a balance is not as simple, and mobile networks will come back to you and say that they can't guarantee a service, or a fault-free service due to the nature of it.

Although the maps with coverage info do meet Ofcom's high confidence standard, it is only ever an indication and not a guarantee so things can change, even temporarily if masts are being worked on or some other interference or permanently if there are tall builds or other structures, trees etc. Not sure how often those coverage maps are updated either.

I would advise maybe comparing with a SIM from another network that might rule out if the no reception thing is just with Smarty (Three) or whether it happens with other networks too (which could indicate other things like congestion etc). If you are getting better signal with those other networks, then as the guys below have suggested it might be worth switching (after you've verified that the performance works for you). It pays to research for your own peace of mind!