UK Question. MOT Scam?

The thieving g**ts.This was going to be a rip off big style.You can pick a headlamp up normally for under �30(From any scrappers)A universal lambada comes in at about �20 (that's what i paid for mine and works perfect).That's the trouble with dealerships they charge you top wack everytime.Unfortunately there really is nobody you can complain to as they haven't broke any laws.They only quoted you a price for the work,its then up to you if you pay it or not.How can they sleep at nights?