Most of that is on me, I haven't given it the love it deserves, but I'm currently rewriting it and will be modernizing it, making it responsive, and adding new features.
replying to a goading competitor rather than an honest now-former customer with a legitimate complaint strikes me as a real classy business move.
just my opinion.
(i'm a customer, I love pinboard, and this affects nothing as far as i'm concerned.. I haven't ever needed customer service -- it just strikes me as rude.)