If you ordered and received a record (DVD) and the (DVD) is blank how do you request a replacement?

I ordered a Civil War pension file. I received it in the mail as a DVD. I received the DVD a few weeks later put it in my computer but the DVD is blank. I called a four times and left messages but haven't received a return call. I also emailed the NARA website and I have yet to receive and reply. How does one go about getting a replacement for the black DVD/CD?