I get my g/f's and her sisters fiestas serviced my a mechanic i use and he stamped the book and staple the ford reciepts into it for the genuine parts used. Dont see why that would make alot of difference. Wouldnt bother me buying a car if proof of genuine parts used and saves so much money.

Ford 3 year service on my mums diesel was £350, i got the parts which was £90-100 and did most of it myself. Local mechanic changed oil and filter for £15 and stamped the book. Saved around 200 quid