Are decompilers a myth?

I bought a program online as an .exe file.  It's intended to "package" my exe game program (a VB6 app.) so that it will run from a web page.  I've tested the program with a number of exe's and it works.  There are 2 problems;  It won't work with my VB6 app and the small company who sold it seems to have flown the coop - no response to e-mails.

My question:  Is there some way to figure out what the program is trying to do?  I could then see why my app. causes a problem.  I understand that decompiling someone else's program is ethically suspect, but as I've paid in full and can't get support, it seems the ethics are a wash.

Is there any way to determine in what language the "packager" is written and decompile or otherwise see what's trying to do?  Thanks