I booked a trip through Viator that was supposed to start very early in the morning. Confirmed it was on before I went to bed. Got up early the next morning to find a late-night e-mail saying the guide cancelled me. Apparently the trip was too crowded. If I would've know, I could've arranged a different service, but it was too late in the week to find anyone. Terrible experience.StayStay User's recommendation: stay away or get some type of confirmation early on.