Again, read the wording on their web site. It explains that nothing is really guaranteed, that all you are doing is making a request. That is to protect them in case something unforseen happens, such as a pipe burst or a bed bug infestation.
I have many times not gotten requests, in fact I have probably not gotten my requests more ofthen than they were granted. Requested any room in the Bayou section of POR: Nope, was put in Mansions. Requested third floor Raratonga at the Poly, got 1st floor Tokelau. PAID FOR PREFERRED AT THE MUSIC, WAS PLACED IN BROADWAY, which is so NOT prefered! Connecting rooms at the Contemporary? Nope!
All Disney guarantees is a room for you, and according to the verbage in your reservation, that is all. It is more like a connecting room is guaranteed, if they are available. You can always argue that you have it in writing, but they can't make a type of room availabe if it just isn't. As the CM at the Music explained to me when I wasn't happy with my relocation, people extend stays and Disney won't make them switch rooms to accomodate people that are not checked in yet.