No, you don't have to write off your helmet when a vizor attachment fails. Neither is continuing to ride without a breath deflector or nose cap a necessity. A Shark can be pimped however you want.
Just about all Shark parts that can get lost, break down or wear out can be found here. Except the helmet shell. If that breaks, we really need to push for a new helmet.
The correct helmet model is invariably listed in the product description, as it goes without saying that you shouldn't tinker with ill-fitting combinations yourself.
The Shark vizors are bundled in a separate product group.
Tip from the RAD-house
A helmet is designed and made to provide 100% protection once. One time. Make sure that one time is not in your garage or at the kitchen table, and put your helmet safely on a helmet donut while you are working on it.