I called out Bgas for the last time. A chap came out and immediately
said that it was the heat exchanger which was blocked up because of
muck in the CH system. He said that BGas would not repair it as it was
due to dirt in the sytem which should have bee flushed out and they
cant replace it anywahy because the part is not availanle anymore.

He said my only option was to get them flush the system (600GBP) and
then have heat exchanger repaired by them at 70GBP/HR. Alternative was
to get a new boiler fitted by them for 3500GBP. He also said that I
was so lucky that I got 12 years of this boiler; they dont last that
long. I told him where to go.

I am totally naffed by all this. BGas have been 'servicing' this
boiler for the last 4-5 years and they have this annual service (if
you can call it that - engineer looking at the boiler with a torch for
5 mins). They never told me that I needed a flush and now that the
heat exchanger is gone, they say that its not covered because the
system should have been flushed. A bit cop-out for them if you ask me.
What diabolical service!