Potterton suprima 80 - Does anyone have one of these boilers which constantly goes into lock out mode? Our plumber has found out pcb problems but Potterton denign this but have updated them - why?We are being asked to pay £250 for a call out charge by Potterton just to identify problem. Our plumber has tried everything else but did find out that over 10,000 pcb were faulty. Have written to Pottertons but got back a standard letter rejecting the claim. Having read some postings it would seem the pcbs have been a problem with other models too. Any suggestions please? Our boiler is only 4 years old.