Sooty gas boiler

I have a Potterton Kingfisher gas boiler, probably about 15 years old. It's given great service up until now, but the other day I noticed a 'flue-gas' smell in the house and sooty deposits on the outside wall above the flue exit (there have never been any marks there before).
The boiler is regularly serviced (it was done just weeks ago) by a reliable CORGI-registered gasfitter, who says there was no soot in the exchanger when he last visited. He's just been back and apparently there is now a lot of carbon in there. He's condemned the boiler and says we need to replace it. But the burners look fine and nothing's changed over the past few weeks.
Is it possible for a boiler suddenly to deteriorate like this? What might be causing the carbonisation? Do I need a new one?
Grateful for any help you can offer!
Mike.
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no, get a new tech, its need cleaned , and adjusted run away from this guy , and dont have him back, sounds like he got something misadjusted when you had him ou the first time now he just doesnt want to deal with the mess of cleaning it
you need a new service technician , not a new boiler
cheers
Mike wrote:

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Mike wrote:

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