I am an avid user of Booking.com and have frequently recommended it here on the Forum. I like having my reservations in one place, I like the search feature, I like that I can cancel or change reservations as I refine my trip plans.
Recently I made a couple of reservations sort of on auto-pilot as I have used the site so many times. Much to my surprise, when I got to the check-out screen, there were two rooms in my "basket." Huh. So I deleted one and went forward. Much to my surprise, the reservation confirmation email said it was pre-paid and non-refundable! I immediately wrote to Booking.com support, but heard nothing for 10 days.
Today a pop-up ad for the same hotel intrigued me, so I followed it as it promised a much lower price and a "lowest price guarantee." I went through the booking process to check it out and much to my surprise, the following popped up in a bubble when I got to the page where you select your room:
To save you time, we’ve selected this property’s typical room type for two people. You can always change room type or quantity below.
Great! To "save me time" they pre-selected the non-cancellable option. This is what must have happened 10 days ago! Not seeing this (since I am so used to the site) I selected another room and ended up with two in the check-out, and of course I deleted the wrong one, not realizing the difference.
I felt scammed and misled, and since Booking.com had not gotten back to me based on my email (I prefer a written trail), I called them. I got a very nice rep who apologized. Said that "they" are always trying new things on the site and she could understand my situation as a long time user of their service. So she converted both reservations to cancellable ones.
So beware of pop-ups and pre-selected fields, but also call if you have a problem. They did right by me.