When I brought my mom and brother to Disney for a few days, I requested a handicap room for my brother. Well the girl at check in was new or a new CP, but didn't really relay the info correctly to us. So when I got to the room, it was 2 beds, but no roll in shower.
I went back up to the front desk and the next girl was able to explain what happened. The handicap room that was available only had a king bed, so they gave us the adjoining room for free to accomadate 4 adults. Which made the whole thing 10 times better.
I want to say I've seen the option though to change to a king bed room on the booking page. Of course that might've been for a deluxe resort in which case they charge you more for it. Come on, the cleaning person only has to change one bed, not two. It should be cheaper.