My parents get their gas from Scottish Power and recently they received a monthly bill for £800. When my dad phoned to query this they said that our gas bill has always been an estimate and for the past few years we have been paying less than we should and that this recent bill was to balance it. Fair enough, BUT... I was under the impression that the suppliers should periodically check the gas meter every year or 18 months - but they said ours hadn't been checked for at least 3 years. I would think that this failure to check on our useage would invalidate any claim they have to this £800 but I'm not totally sure. Anyone have similar experience? Anything we can do?