I never received a letter like that either, but like jpeka65844, our KTTW card still worked for additional Fast Passes. In addition, since I had an AP and DH had a 4 day ticket, we could get additional Fast Passes via our ticket media, meaning we could get: FP+ reservations, plus 2 Fast Pass tickets each for our KTTW and our hard copy ticket. Now, we never got any Fast Passes with our KTTW tickets and I think I got all of 2 fast passes with my AP for our entire trip, mostly we just used our FP+s and even those weren't always necessary since in some parks we do mostly theatrical performances as DD is barely 36 inches.