Have done numerous tours with Viator. Usually OK but on last booking really hit rock bottom. Booked a ride from Roma Central train station to port. Sent two emails to operator with the time of arrival of train. That morning he calls me and says that my 12:10 arrival is too late, the ride is leaving at 11:30. Fine please cancel the pickup. But for an extra 50 euros we can accommodate you. Don't bother, I'm at the train station already and will take the 12 euro train instead of 110 euro ride. I reviewed him just repeating this story. He contacted me through Viator and insulted me calling me a piece of s--t. Great customer service. Sent an email to Viator with his comments and the email I sent to provider with arrival information. No response after a week. Called their service number and talked with a "service" provider. It was my fault and there was nothing they could do. Asked for contact information for a manager. Nope. If something goes wrong with Viator near impossible to make contact.