From my experience VBA looks for sav file named exactly like the game in the current folder. So try renaming the sav exactly like the game without the extension.
Then just run it.
it's really quite easy to transfer your saved files from phone to pc and back. I plan on making a short tutorial video on how to do so since I've managed to get it down to a T, doing it in just 3 minutes even WITHOUT a cable to connect the my device to the pc.
One thing to note, you might wanna get a hold of the latest version of basic VisualBoyAdvance for ...