Looking for advice on existing boiler and BG Powerflush. Bought london flat a couple of years ago with Halsted combi. Have BG contract and nothing but trouble with boiler, continually failing with hot water heat exchanger blocked. BG now refusing to replace heat exchanger any more and suggesting powerflush as the solution. BG have declined to quote for new boiler, saying vent is to light well which they cannot fit. All seem to say that existing boiler is very basic and we should replace with say WB, will also gain better hot water flow rate. Existing boiler is sited inside a kitchen cupboard only 300 mm deep. Any suggestions for new boiler, are any compacts any good or should we go for WB or similar and alter cupboard to suit. Thanks in anticipation