Posting this because Baxi have been useless. Boiler is 13 months old and the burner fails to light after the fan has started. I can sometimes get it started but only on maxumum and if the burner stops for any reason it will not relight for several hours/days. An engineer has visited but couldn't find anything wrong and baxi want to charge a fortune for one of theirs to visit. Is it worth changing the PCB?