I buy the collection becouse its said its on stl but its was not

Hello, I need format .stl and I paid 35 USD for this format file. I can not open .3dm format file Please fix this problem and let me know as soon as possible Thanks, lesmore Hello, We use Accu Trans 3D Best Tools to convert 3D files. We can not transfer your files to stl format, We can not open This is picture file ? I lost money ? Please Fix This, lesmore