Perhaps this is naive (and you may be doing it already), but do you provide different "QoS" for your paid/free users? Have 2 addresses/contact forms with specific promised return times?
That's precisely what I do -- I have to -- needless to say deprioritized users feel fully "ignored".
That said, you can't please everyone... if you're the one left serving the lowest-IQ users with the lowest-or-no-budget, you just give others an easier time making good money off more savvy software users. Before you know it, you have to close down shop for good...
