Hi so glad I e stumbled upon this community. I might actually get something resolved as calling goes no where! MY hot water gas bills have been double since the Feb 2017 issues bill. We used to use just above 7000 litres and now we somehow use 14000 litres. Plumber has checked the unit and cannot see any sign of a burst pipe. We have not changed how we do things. Calling up and being told someone will contact me back NEVER happens. Biggest fob off ever.