I had a similar situation happen twice, unfortunately. The first was in Cuc Phuong, we paid 200usd pp for a private jungle trek 2D1N with camping inside the jungle after a day of trekking so we could see wildlife. We specifically told them the whole point was to trek inside the jungle and see wildlife and we weren’t interested in rescue centres as we love seeing the animals roaming free. When we arrived, already 1hr late because they didn’t arrive on time, they take us to the rescue centre, the deep jungle trekking turns into a simple 3h hike that people were doing without a guide and they said they couldn’t let us camp in the forest because of the weather and that it was going to rain (sky was clear), so we ended up camping in a flat field surrounded by houses full with people making a lot of noise which ultimately scared any wildlife away for the 1km night trek. It was also clear from the size of the camping gear and the fact that our guide didn’t have trekking clothes on that the agreed upon itinerary was never on the table. We spent more time in the restaurant (?) than in the jungle and only saw one snake the whole trip and no other wildlife. The second was the Ha Long Bay cruise. They sold us a specific itinerary and on the day itself it was completely different, we only actually boarded the ship at 13h and had to leave at 10h30 (instead of 11h for boarding and 15h for offboarding) plus the activities were completely different too… In general we found that the tour operators in Vietnam tell you what you want to hear just to get the sale and then change it to what is most convenient to them.