ok Marky66 you have a boiler thermostat inside the boiler which can be accessed by lifting the small panel at the top of the boiler straight up. make sure the power is off as you'll have 240v wiring center exposed., Its a small pin like control with no handle, make sure that this has been turned fully anti clockwise! Also you'll see a small red button on the right hand side of this boiler, just to the left of the fan, press it to see if the boiler has locked out here. If you are getting hot water the problem should not be expensive as the major componants are working fine. good luck.