I've got a fault on a Baxi boiler where the hot water either doesn't heat or if it does it is only for a few seconds then goes cold again. It seems to work fine when the CH is on. A fault light appears under the 70 degree indicator and looking at the manual (which may as well be written in Russian) I'm led to believe it's the Hot Water Temperature Sensor. From looking at other threads it seems to be a common problem but not a definitive or simple answer. I am worried that if I simply call a plumber I will be charged for all sorts of parts that I don't need. Therefore, would someone be able to advise on the likely solutions and if there is more than one option then a guide price for fixing this. If there are any plumbers in the Doncaster area that are interested in taking a look let me know!