Meters aren't perfect
I once had a gas meter than ran slow- I had lovely low bills for a few years - thought it was due to the 3ft walls of the cottage I lived in - until the meter started running backwards - and was replaced
At my next property I had huge gas bills and blamed it on being a gable end with high ceilings. Eventually I asked for the meter to be checked. I had to pay a fee for the check but it was refunded when the check revealed that it was faulty. A refund was calculated on the percentage it had been found running fast, but that refund only was backdated for 2 quarters.
Ah well - swings and roundabouts!
Ever since, I have monitored my fuel usage. It pays to discuss usage with neighbours with similar sized property and lifestyle usage.
All meters (gas AND electric) are capable of developing faults.