And parts are roughly £600. Do you really want to spend that on a 10 year old boiler?
Ideal will do a fixed price repair but even that's £450 and on examination if even more is wrong (probably expansion vessel which is a boiler off the wall job to repair), then even they will give you most of that back and tell you they can't fix it as it's beyond economical repair.
Save your money and get a new boiler as it would be better in the long run.
Trust me.