Sorry just to elaborate, £38.16 is the cost inc vat and 10% voucher discount for 5 gallons of Castrol or Fuchs, 5W30 Fully synthetic inc filter, disposal etc. Its an all inclusive price where I can observe the work. This is for my 2.0i. The £93 was the quote from an Indy!
No I wont get a dealer stamp but in all honesty, this is a 2008 car with 70K miles on the clock, 3 owners inc me, I'm not going to have a dealer hold me to ransom just for the benefit of a stamp. I intend to keep the car.
In any case, irrespective of how much you pay, the only way you can guarantee what's going in your engine is to rock up with the oil yourself.