On the phone Saeed identified the two most likely faulty parts. He had one part, and before he arranged to come, he checked that he could get the other part immediately, if necessary. He told me how much he would charge, depending on the part needed.

He came the next morning and completed the work efficiently and professionally.

Good work, fair price, cheerful manner, and most importantly,
he did not suggest (as another plumber did) that it would be best to replace the boiler; that would have cost 12 to 15 times the repair bill.

He deserves to thrive.