I cannot work this out. We are disputing an enormous gas bill based on an inflated estimated reading. I am trying to work out exactly what we do owe (actually how much we have overpaid and what we are due back!). The bill period was for 33 days. The imperial meter readings were 0558 on day one and 0570 on day 33. The kWh rate is 0.18p, the daily standing charge is 50p. I think we owe £16.50 in standing charge and £69.50 consumption, a total of £86. Am I correct? (for clarification the invoice was for in excess of £400 quid). Trying to reach resolution through the ombudsman for various reasons and want to get my facts straight.