Looking for recourse - Brosoft refuses refund

I purchased a media converter from Brosoft a while back. The software isn't functioning as I need it to (it's not recognizing all the audio channels, and thus only exporting the camera mic audio), so I requested a refund. Even though it has a 90-day satisfaction guarantee, they refuse to refund me. I've probably sent them 10 emails, with fame grabs and very elaborate explanations that the fault lies with their software, and that I'm not satisfied, but all to no avail.

As I'm struggling to get my refund, I'm looking for other forms of recourse. But I haven't been able to find any site to lodge a complaint, or flag them for untruthful advertising or anything.

If I'm not getting my money back, I at least want to make sure everyone knows to stay away from them.

Hope anyone can help.

Thanks.

Petri