contact Citroen and explaine who tested it as I think some garages interpret the diagnostic form as a type of price list.
Your best bet is to contact Citroen main company not the dealership or garage.
Tell them exactly as you've expertly put here and anything else you have as amunition throw that in and then see what they say you may be lucky and for good publicity if the vehicle is not too old get it done at half price or even free in the present financial climes.
Bob
February 2010