Baxi solo RS wall hung boiler installed 13/14 years ago. Not combi - i.e.
has hot tank and header tank.

The pilot light does not stay on when the knob is released, even after 2
minutes or more rather than the 10 secs they say, so cannot relight the
boiler which went out for reason not known. The instructions say to wait 3
mins before relighting the pilot but this does not appear necessary, so I
can light the pilot but only by holding the gas knob in.

Don't know if it has overheat cut-out. I can't find a reset knob though.

This happened 6 months ago and the plumber replaced the gas control (?) -
that's the bit with the knob you push in to light the pilot etc. He said it
might be another part which is more expensive to replace.

I thought boilers were reasonably robust but if this keeps going wrong it
may be better to simply replace it.

Questions:
1 Is the boiler at the end of it's natural life and should be replaced?
2 If so I would want to replace like with like as the simplest option - are
there new regulations altering the type you can replace it with?
3 If not, what parts are likely to be needed to get it working reliably? -
No sense in keep calling out the plumber who does seem good.
4 Is there anything else I need to consider? My wife would like to rip the
whole system out as she doesn't like central heating but it would knock
£30/40k off the value of the house so I'm against it.

Many thanks for your help & advice.

Hontres.