Everyone has to make a living today so the price is up for grabs. Once you sign the agreement, without asking questions, you are committed to their service.
IMO....she should have asked, up front, what the charges would be before proceeding with the service.
The only question is.....Did she REALLY receive Mobil 1 EP, or just some bulk oil from a drum. This is where the problem starts. If people are informed that they have been serviced with "full Synthetic", EP, motor oil and they run it for 10K+++ while it was truly serviced with only conventional motor oil.
IMO...she should make sure that the service manager signs off, on the detailed service receipt, that she was serviced with Mobil 1, Extended Performance 0w-20 since she plans to have the oil analysed at 10K.
That is a professional way of putting the dealership on notice that you properly maintain your vehicle.
IMO...She should go back to the dealership and make sure that they comply with her request, or else call the credit card company, if charged on a card, to refuse payment. The credit card company, if it is reputable, will call the dealership and ask them to do as you wish.