I was unable to cancel my mexican temp vehicle import on exiting Mexico because there was no Banjercito office at the Tijuana border crossing as I had assumed. I have previously exited Mexico with a vehicle at Nogales, and there was a Banjercito office located at the official border crossing. I assumed this would be the case at all border crossings.
On crossing at the Tijuana / San Diego crossing (and waiting for 3 hours in line), I did not come accross the Banjercito, and of course the border officers were not able to assist me at all.