Should I have my 2003 Mercedes-Benz CLK's plugs changed?

I have recently purchased a 2003 Mercedes-Benz CLK with the 2.6 V6 engine. It does not appear to have had the spark plugs changed since it was manufactured. It has done a genuine 46,000 miles with a full Mercedes-Benz service history. When should they be changed, and is this a difficult job? My local garage wont do it because they have heard stories of the plugs breaking in the head. Is this true?
It's a big job because there are 12 plugs. Solid of your local garage to have refused the job. If you live anywhere near Basingstoke, Tony Purslow is good for this sort of thing.
Answered by Honest John on

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