Sorry, I can’t really help you. You’re breaking the license agreement as Linotype requires a license to use Helvetica Neue on your site and that is offered on fonts.com.
Note: Although it is installed on your computer, it does not grant you permission to upload those files onto your server. Always check the EULA of the font you want to install to make sure you’re not in violation.
Your only other option is to set Helvetica Neue locally within @font-face if it’s installed on their computer, otherwise serve Helvetica or Arial.