Sorry to hear. Seems like you do not have comfort access. This kind of thing will never happen if you have comfort access. Some people hide the spare at another place in the car. But still BMW assist should have opened it right away.

I remember reading somewhere that a guy with comfort access(or whatever Acura calls it) on Acura put his stuff in trunk but the trunk would not close. Frustrated with it, he starts driving to dealer and half-way remembers that he left the keyfob in trunk. Keyfob out and bingo.