We first arrived at 11:30pm after a long day of flying - we’d stopped for food and had hoped to have a quick and easy check in to go up to our room to eat. We typically have no issues with hotels.com bookings. The lady at the desk clicked a few things, gave us our key cards, and then forgot as we were walking away to have me sign a form (this whole process took 5-7 minutes). I sent my partner up to the room while I signed the form. He called me and said “there’s a tag on the door that says ‘not ready’”. By the time I made it up he’d tried opening the door but it was safety/emergency latched and we heard someone IN THE ROOM! They gave us keys to a room with a person in it - thank God I was with him and not by myself, and thank God that person had the latch pulled. We went back downstairs a little confused and shaken and the woman at the front apologized, then spent at least another 15 minutes clicking on her computer to tell us that she doesn’t have any rooms with the same bed size. At this point my blood sugar was low, we were exhausted, and I was trying my best to stay civil. Told her to put us in whatever room they had available and we’d talk to the manager in the morning - funny how with the mention of a manager we immediately were put in a room. The manager then told us she wouldn’t refund any amount because we booked through a third party. Overall one of the worst, and most dangerous, hotel experiences I’ve had yet. The view from the room was nice and breakfast was good.