I contacted Thames Water and asked it to pull the plug on these repeated mailings and get your bills sorted out once and for all. The firm quickly apologised for the mistake and deleted the £707 direct debit demand.
It confirmed that you would instead be paying a more sensible £20 a month. A spokesman said: “Our aim is always to deliver brilliant customer service and we have fallen short on this occasion. This was due to a billing error, which has now been rectified.” The company has paid you £50 as an apology.