I generally regard British Gas as the worst of the worst when it comes to customer service. The inability to speak to someone who can actually make a difference is staggeringly difficult.
Our smart monitor stopped recording some weeks ago so I have less visibility of incurred costs. The fault is allegedly due to a software issue on the meter so this also impacts on data being fed back to the online account. The guy who came to service the boiler didn't want to get involved; he was part of the "It's not my job" brigade, the online chat route has proved futile, and some call centre chappy could not advise on a fix (at about the tenth attempt at trying to reach someone).
The app doesn't work for me either. The reason quoted to me is that it's not able to cope with two addresses being paid from one account.
Tinpot organisation of the highest order.