I will never again use Booking(dot)com after I booked flights through them earlier this year. (Normally, I'd book directly with the airline, but there was a reason I chose to do it this way. Never again, though.) Even though I entered my name correctly, the booking ended up with part of my name missing. Meanwhile, I had purchased an upgrade through the airline. I realized the error immediately afterward, but the airline wouldn't help me because I'd booked through a "travel agent." Booking "corrected" the error by cancelling my booking and redoing it. (Apparently, according to the airline, this is not how they should have made the correction.) In the process, I lost my upgrade. Booking attempted to assist, but they were unable to get the airline to budge, also. In the end, they were willing to let me lose the money I'd paid for the upgrade. I don't know if their system made the original name error, or if it was the airline, but I strongly suspect it was Booking. Regardless, their method of doing the correction was wrong. (It also separated my booking from my husband's, which had the potential to cause problems, although it didn't.) They did not take responsibility for the error. They were willing to let their customer lose out, instead.
Posters here often advise to book directly, rather than through aggregators, and that's very good advice. I do occasionally book through aggregators, because, sometimes, that's the only option. (A small tour company or venue might not have their own website.) But it will never again be through Booking, for me.