A few years back, I posted Smart Meter Communications - or NOT? Now a closed item.
My issue has now been solved.
After getting nowhere by telephoning E.on's Customer services, following an email discussion with their complaints dept, they set up an appointment for last week and the cure was to fit a new Gas Meter and Electricity Meter with a dual-band HAN so besides the previous 2.4GHz signalling, communication between the two meters was now available on 868MHz.
And it works! Job done!
Clive