THIS. We had a similar experience. Our last trip to the other coast (Disneyland) was awful on so, soooo many levels. I did write a letter because I really just wanted to vent. I've been going to Disney my whole life and the immense sadness I felt that my "happy place" was no longer...well happy, was so tremendous....I just had to tell someone. I was fully expecting a generic letter from a "grunt" as well...but what they did to remedy the situation was FAR beyond anything I could have ever hoped for! It took us from questioning if we ever wanted to go back to Disney at all, to marveling at their insanely awesome customer service and highly anticipating our next trip! You just never know what writing of your experience will do...and if nothing else, you can be happy knowing that if they keep getting so many complaint letters (strength in number, people!), they will see that there are big issues that need fixing, and things will start to change...nothing like disgruntled dollars on the line!
We just had something similar happen. Our recent trip was not good. After we got home I emailed Disney. Writing letters to complain is something I never do. Although, I felt I needed to because Disney is not what it used to be (we go to Disney A LOT). We left there sad, missing the old Disney. I just expected a generic "we are sorry" email back from them but last night they called me. I told the girl all the problems we encountered during our trip. She listened, took notes and thanked me for taking the time to talk to her. She said they needed to hear from their guests. Then she sprinkled some major pixie dust on us. I was blown away! Before talking to her last night I had totally given up on Disney. I had lost all faith in them. Now I am looking at them differently....like I used to. I am starting to think the old Disney is still there.
So, if you have problems contact them. That is the only way they will know. They will take your comments seriously. If everyone starts writing to complain they will do something. They don't want to lose guests (she told me that last night).