I always have a Plan B. Actually a Plan B, C, D, and E. However they do not know it. I do not contact them until I need them. Usually these are regular, local guys I know I can call and set quickly an arrangement for the next coupe of hours.
Maybe more accurate than talking about Plan B, it is to always keep a To Do List of local guys who can save you, if you are giving your first steps and do not have yet regular guys in your phone book.
I was in a similar predicament in my last trip to Buenos Aires, where I do not have regular guys anymore. When the first guy in my list was a failure, I just moved to the second one and meet him.