i agree with you i always serviced my old car never got the book stamped so realistically it had no service history i lost about £500 on it for this but if you mount up the costs of services over time owned then see the difference in price does it really make a difference,i never got round to offering a service manager £20 or so for three or four stamps in the book lol.
My car is missing one stamp in the service history and when i attempted to trade it in a couple of months back, it was suddenly worth about 500 quid less than it had been worth when they didnt know about the missing stamp.
If your going to do one service it yourself you may as well do all of them yourself, thus saving the difference in value over the years of ownership against servicing costs. Just dont miss the odd one and end up with part service history because you'll end up about 400 quid down on the value of your car for the sake of a £100 minor service...
And they deffo wont stamp the book for you no matter how much you plead with them, its fraudulent unless it was actually done at said dealer....