I signed up to take this tour on Sunday, July 28 but it turns out the tour doesn't run on Sunday or Monday. I didn't find this out until I left a message at the office of Brazil Trip Turismo after waiting at the pick-up point for 45 minutes. They apologized, refunded my money promptly and offered me a deluxe tour if I was ever to return to Rio, which is quite unlikely. If I had known the tour didn't run on Sunday or Monday, I would have rearranged my short time in Rio to take the tour a different day, but this information was not posted on the activity page and the calendar was obviously messed up. It sounds like it would have been a terrific tour, but I never found out.
It's not clear to me whether the tour operator made the mistake or Trip Advisor/Viator, but it was very disappointing to have the date confirmed several times by text the week preceding the tour, only to be left sitting in a hotel lobby for 45" on a Sunday morning with no one showing up from the tour company. It was a big waste of my time and money getting myself to the pick-up spot and disappointing too because it sounded like a great tour.