I work in this industry and actually we’ve found from online experimentation customers generally don’t want to tell you they dislike something. The expectation is customers get what they like (relevant) and sometimes they want to express stronger affinity for specific things. The converse hasn’t shown to be true. Generally customers don’t have a clear picture of how their explicit signals impact recommendations. Thou…
So I tried to contact eDreams, which requires a trip reference number.
Since I couldn't pay them for a plane ticket, I didn't have a trip reference number. So all their ticketing and phone tree systems would hang up on me.
eDreams customers, evidently, don't want to contact them without having a trip reference number. And they know this for sure because they've never had a customer contact them without one.