We have a combination boiler. It's only 7 years old, but lately it has been losing pressure through the over-pressure valve.
That should have been a cheap, quick fix, but it turns out that it's not that, it's probably the expansion vessel.
The plumber says it's very hard to get to on those models (it's a Baxi) and says that replacing the whole boiler (£1200!) is probably going to be less trouble in the long run than taking the whole thing off the wall, repairing it, and putting it back.
How long is a boiler supposed to last? More than seven years, I should think. And what boiler manufacturer doesn't make its bloody £$!£%%! boilers too awkward to repair when a part wears out?
Daniele