We used Viator for our Thanksgiving vacation in Puerto Vallarta. We had seven people arriving at different times and days, and needed transportation to a private residence south of Puerto Vallarta. Admittedly the reservation was complex, but I spent over and hour on the phone with a Viator representative arranging and confirming our and our guests transportation. When we arrived in PV, the subcontractor Grayline did not have our reservation. The representatives were very courteous and after a sort delay we were sent by taxi to the house. Concerned my guest reservations may also have not reached Grayline, I was told to confirm with Viator. After another 40 minutes on the phone first to Viator, then to Grayline the other reservations were confirmed, and our guests reservations were executed without issues.