The ONLY reason companies respond to user feedback is when they fear it's impact on sales. That's why, without being "childish", it never hurts to firmly let the vendor know you are unhappy with their product - to the point where you will take your money elsewhere.

I usually start with technical support for a complaint, in hopes that something can be done to fix the software. If this doesn't work, I move next not to the technical supervisor, but to the sales force. They tend to translate dissatisfaction more quickly into lost sales than do technical people. I have found this to be an effective strategy for getting changes made - unless one is dealing with Microsoft. 😉