Hi there. I need help. We had purchased Project 2016 Std retail box through Staples a few years ago. I had to replace the hd on a laptop. I still have the retail box and product key. However when I try to download the software through office.com/setup I get the message saying "Product key already in use." I've tried calling Microsoft support, but I keep getting transferred in circles. Is there anything else I can do besides pay $499 for one-time support just to unlock the product key? We paid $749 for the Project 2016 Std retail version.