My mother died last January, gas company served the estate a bill for £40,000. This was in spite of there being no functioning gas appliances in the house for 3 years. Seems their agent had misread one of the digits on the meter 4 years back and when I provided the final reading it was lower than that previous one. They deduced that the meter must have hit 999999 and looped back around to reach the "lower" number. Took 2 months to get them to correct that.