I have only ever got 3 replies so far have written to a few but I have met lots of the cast from Paul, John, Chris, Ada, Steve, both Links, Esther, Lyn, Samara and can't think who else. Still hope for some letters.
I'm sure you'll hear something from them sooner or later. Sometimes they're just really busy and have a ton of fanmail to get through. It once took me writing to Rebecca Breeds twice, after a year of not hearing anything i wrote a second time and that took a few months.