Britony combi se 40 60 80 fault

[chris3216]

Hi all I have a britony combi se 80 with fault 40 60 80 had british gas out to repair under homecare cover but they can't seem to repair it. They have been out 7 times so far and fitted a new pump heat exchanger air pressure switch and a pcb. Does anyone on here know what else could be the problem because fault 40 60 80 is fan on but air pressure switch not activated