@DaveC You are exactly right, the electric meter does the communication to SP. The Display only works locally in your house and does not say anything reliable about your costs and bills, they are calculated by the SP system. You are also right in that the different databases do not communicate to each other very well. SP keep the accounts section ring fenced for obvious reasons. The result is different data from the app and displays. The only truly reliable cost data is from your bills which are all online as pdf files.
I think I'll give up on this for the moment as I'm just going round in circles with them. Hopefully at some point they'll be able to make it work.
@emloco You just go round in circles if you try and phone them. They seem helpful to start with but it soon becomes apparant that they don't have a clue what's going on. You get a different conflicting explanation each time you phone, and when they try and adjust your account to make the gas readings work they stop the electricity reading working too!
Well after having given up both the gas and electricity meter readings have been updating for the last couple of days. For some reason the gas reading says "Successfully retrieved from meter" in a box next to it when I look online.
Fingers crossed they will stay working.
@avonroyd There are many reasons why smart meters fail to send readings. Do a favour and read the meter and send the readings. You have to press buttons on the meter to get a reading.