In April I called out the plumbers when my boiler didn’t heat the water. They fitted a new part, but the problem reappeared within an hour and they came back and fitted another part. Two months later I had the same problem and the replacement part was found to be faulty. I was amazed to get a bill for £156 to replace the faulty part. Do I have to pay this?
I think you should suggest that the plumber takes this up with the supplier or manufacturer of the faulty part. If the plumber is adamant that you should pay and you refuse, they would have to sue you in order to get their money, and I think the court would agree with you that plumbers should supply parts that last longer than two months.