If you're in warranty, and you haven't tampered with it, send a support ticket:
http://viking360.com/support/support-tickets
If you're still in warranty, and you tampered with it, Viking360 will not touch it.
If you're out of warranty, and you tampered with it, Viking360 will not touch it.
If you're out of warranty, but it's an easy fix, like the sync button got stuck inside the controller, or a tac, viking MAY repair it for you, but you would pay shipping.
If you aren't eligible for any of those options, try to contact Fredrow, he has his own business, which, if I'm not mistaken, is affiliated with Viking in some way. (He may not fix it, but you can always ask him.)