We booked about a week in advance via Tripadvisor and got confirmation shortly after. A day before the tour, a reminder email was sent to make sure we would be there on time. We were 9 people, so we took 3 taxis from the city center to the pickup location which is a bit outside, arrived there 20 minutes in advance.
No boat there, so we waited a bit and then called the contact number. Surprise, they didn't know that we were going to take the tour that evening and were quite confused. Told us that they have a "bad connection" to Tripadvisor, so they regularly don't see tours booked here in their booking system. Someone else booked the same time slot directly with them, so the boat wasn't available for us.
We were offered to take the tour the next day, which was our departure day, so that didn't work either. In the end, we just got our money refunded, which fortunately happened very quickly. We wasted quite some time with this and also some money on the 6 taxi rides to the location and then back to the city center, so I can't recommend this at all.
In my opinion, if someone offers a service on a platform, it is their duty to make sure that they are able to fulfill any confirmed bookings made there.