Thanks, Rosalind. I was worried about the old "They don't make the parts for that anymore" routine. I think the fact our service/repair contract is with an insurance company, and not with the manufacturer may have saved us. It can be a palaver organising a call-out (1. Phone insurance company. 2. Get job number to give to boiler company. 3. Phone boiler company with job number to arrange appointment. 4. Service or repair carried out and boiler company charge insurance company directly). I'm speculating, but perhaps failure to effect a repair would have resulted in no payment to the boiler company. I'm sure they weren't worried about how many new components were being fitted if they were all going to be charged to the insurance company anyway.
Forgot, we had one other problem. The 7-year-old grandson of our friends and neighbours, unbeknownst to us, decided to do us the favour of clearing snow from our driveway. Unfortunately he cleared the snow from the front half to form a large mound at the back, rendering that part unusable. (We still gave him a small recompense for his thoughtfulness).