I'm tempted to change gas supplier as British Gas has increased my direct debit from £15 a month to £50 a month with minimal explanation. Perhaps another supplier would at least give me the courtesy of explaining how they arrive at the amount.

The letter says: ...we regularly review our customs' payment plans

I find this inadequate - what figures are used? I reviewed my own figures and the highest average is £54 a month last winter. Even with prices rising, it seems unlikely that I would use £50 a month on average over the next 6 months, and it would be hugely excessive over 12 months. Based on the last 12 months, the direct debit should be £35 a month plus the price rise - and the standard letter that has so little information should at least state the estimated average price rise for the next 12 months.

A wooden spoon to British Gas for customer service, for appearing to think that customers do not want proper explanations. Worse, perhaps they are still trying to use direct debits as a way to boost the cash supply.