Can I sell a product key if I can’t use the product?

I purchased icalendar and I can’t use it. They told me that I could print on tabloid paper and that it would print at least 15 events in one day. It does NOT. I know that it can be used on the web, but we already have something in place and do not need this. I have tried to get my money back form them as they claimed (via emails) that it would do what I needed it to do. My delemma is I paid for it, but since we can’t use it I hate to ask the church to pay me back. If I could sell it even at a loss I could live with that. The can’t get this company to respond in any way to reimburse me.