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.
Yes Its always good to send another letter if you dont hear anything after a long time. I did that once as well I got my reply which was nice yet to me any reply is nice.
Good on you for Bec sending you a reply