British gas nightmare

Bellatrix381

My partner moved into a new tenancy in August last year and was automatically put with British/scottish gas. He's had nothing but issues with boiler not working, no gas, faulty radiators. He moved to smart meters for duel fuel about 2 months ago and the electric has been working as it should,  however the Gas accepted the first online payment I added in January. Credit was added within 30 mins and it was same online as his meter display, the amounts matched.   Last week I topped it up again, Same online account , (except his display and online amount didn't add up before this time).  It hasn't been added to his prepayment amount. It's not under top ups anywhere. It sat pending for 4 days with my bank, it's now cleared my bank but still hasn't been added to his account.  
He went through all his options pm his smart display and it has a status 23-3 meter connection message. He checked all through it and the only thing he could see was the WiFi so he's turned it on under the belief that maybe it's not connected to the network so therefore maybe payment hasn't been able to get through. It doesn't explain where the money is now though and why his electric has been fine but he just can't get his gas to work. He has an electric smart card but didn't receive a gas one so at moment online seems to be only option.  I don't have smart meters, I'm personally with sse and they didn't turn up to install mine so im stuck on how to help him.  I'm starting to feel happy about that though tbh. 
Has anyone got any ideas? He wants to switch to SSE but the recommendations say not to switch just now.