There are also pharmacies all over, and many pharmacists are quite knowledgeable. They will be more than fair to you. They are located on the Costera. In the U.S., time share sellers are merely annoying, but in Mexico they can be downright obnoxious and lying. Never run after a bus, another is right behind it.
Most busses are about three pesos, and they give change.
If he shakes his head and drives off, try a little bit higher with the next one. There is always another taxi. The worst thing you can do in Acapulco is rent a car. It is unecessary, given the great bus and taxi service. It is guaranteed to get you lost.