That dealership was literally trying to screw you over.....
I go to BMW of North Scottsdale and if my car yells at me to add a quart of oil I just drive into the service area and they pop my hood and pour it in. No questions asked no checking the key fob except as of recently they now have to take my car to the service bay to do it.... Must be some policy with BMW. It still only takes a minute so no complaints on that.
You should never have to buy anything to maintain your BMW... That's why they have the plant in the lobby with the sign saying " This cost more to maintain then a BMW."
Glad you told that stealership off