Theoretically they have to. If you don't receive email on your domain registered email regularly your DNS provider can make changes that will break all of your stuff and you won't know because you never received the email they sent two weeks before the change.
I noticed a France origin on all the contact info so you might even get a response tonight if someone is at least polling on that address for hits.
The next step would be to register a complaint with Network Solutions as they are listed as the technical contact. While Network Solutions is dreadfully slow by email/web a phone call can work wonders.
If you want/need additional help on this let me know. I'm quite happy to do this stuff as it's ... well ... something I do a lot of.
- Rex