Worcester 24i Boiler?

My boiler is about 15 years old it keeps clicking itself on and off and wont sustain ignition. It is making a wailing noise and it sounds like the timer switch is grinding. I am unable to use the timer as it sometimes doesn't ignite. I need a local plumber/gas registered engineer to come and have a look at it without much success at the moment.
Can you help. I live in Blackburn Lancashire