I bought an NA5C yesterday at EuroBoox and I'm really worried.

As the title says, I made my purchase yesterday and now I'm reading a lot of messages about problems with these people that have alarmed me. 

What can I do now that I've already made the purchase? Can you give me any recommendations? Because I've read about people who haven't received their packages in months, or empty boxes, and well, lots of things that I'm really worried about.

Thank you...