Sorry that you had so much trouble finding your tour outfits in ports.  We almost always take shore excursions through the cruise lines even though they may cost a bit more.  We don't want any surprises when we reach a port.  Only one time did we have trouble finding our tour in port. Someone eventually helped us.  It was on their private island so it was hard to figure out why there wasn't anyone from the cruise line on the dock to offer directions.  I guess they were all gone to the beach.