Online petitions are pointless and are not worth the hard drive space they occupy on the server(s) that host it.
Petitions in general are ignored. They generally (but not always) represent the views of a vocal minority. While many of us on this forum support what this petition says, remember that there are only approximately 1,000 of us registered here. A small portion of those are actually active. Let us be generous and assume that there are 2,000 moderate to hard core Vanessa fans total. 2,000 people? Big friggin deal. Most people don't care. The general public is what the record companies care about. Not us. We're just a nuisance they put up with because we buy some merch, go to concerts, and do some promotion, all with little cost to them.
Secondly, petitions online are even worse. It's far too easy for someone to sign it twice. It's far too easy to sign, making people go, "awww... what the heck." It just amounts to a bunch of whining that will never make it anywhere.
If you really want to support Vanessa, here are a few things that you can do.
Firstly, go to concerts. V has been playing tons of small venues. While that's a nice thing because small shows are cooler, she'd doing small shows because she can't fill bigger places on a regular basis. Contribute to the numbers attending her shows.
Secondly, play her music in front of people. I've gotten so many comments about Private Radio. At least five or six people have bought Harmonium because they've been interested in music that I've been playing. Her music speaks for itself. It will do all the selling you need. And if the person isn't convinced, they probably wouldn't enjoy the music anyway.
Thirdly, don't be a weirdo street teamer. Freaks get weird looks and few converts to their cause. I've seen one too many overenthusiastic weirdos shilling for an artist. It's a turnoff that does no real service to the artist. You just get laughed at.