It is difficult to be sure, but these are my thoughts.
I think your problem may be that “How is your trip going?” sounds like polite small talk, so people want to answer in a polite way. The questions about the guide and driver are similar. Many people don’t like to complain or be negative in response to this type of question. It is like when someone asks, "How are you?" - we usually just reply with, "Fine thanks" or something similar.
Personally, I would be more direct. Be clear about what you want to know and why. You are asking because you want to fix any problems immediately, right? If so, tell your clients that.
Hi, this is Marinacat from the Top Tour company, I am calling to see how your trip is going. (You can make some small talk here or just move on). If you have time, I would like to ask you specifically about some of our services, so we can fix things if there have been any problems.
Then you can get into specifics about the driver, food, tour guide and so on. Let them know that no matter how small the problem, you want to know about it.
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