Smart meters are a con. They are only effective if you stay with the company that installed it. Move to another company and they are no longer fully functional. This is because every energy company installs a smart meter compatible with their own software and no two smart meters are the same, nor are they mutually compatible.
British Gas installed a smart meter in our house. It worked fine while British Gas was our gas supplier, no problems at all, but 18 months later we changed fuel supplier and now our meter has to be read by a meter reader again. That may be why your son is having a problem Mildred, Did he change supplier?
I think that smart meters are over rated. Several years before we had a smart meter we installed an 'Owl', a device that measured our electricity consumption. We put it in a prominent place in the kitchen. All it told us was what we already knew - that we were careful fuel users. In six months we never once looked at the reading in horror and rushed round turning lights and devices off. When we got the smart meter we put the display monitor in a cupboard out of the way
Smart meter or no smart meter we still do what we have always done, get a quarterly bill, check the meter, send it back with the correct details for recalculation, if necessary, and pay by direct debit. No problem, no overpaying, no problems having to get overpayments repaid.