This may be a much bigger issue than you are anticipating! I started my engineering career as a seatbelt specialist with Ford Motor Company. So here are a few key points for your puzzle:
Seat belts are manufactured and tested as a complete set and must comply with a specific Federal Motor Vehicle Safety Standard (FMVSS)
When "replacing" one side of a seatbelt system, you usually have to replace both sides, since they are provided as a complete set, fully tested.
Based on the pic you provided, it looks like the plastic collar which failed is built and shipped as part of the seat belt assembly. I can't see a path to replacing just the plastic collar.
Lastly, if ANY PART of the seatbelt assembly fails, the manufacturer is usually quick to replace the assembly, since failures that discourage people from using the seatbelt are considered a "system failure". For example, when a belt retractor fails allowing the belt to get caught in the door and become soiled, that is a complete failure, since it discourages the user from wearing the now dirty belt.
FMVSS are "no-compromise" items. The fines for selling vehicles that do not comply are meaningful, and often lead to broader investigations and ultimate vehicle recalls.
I would lean pretty hard on the dealer to replace the belt, and not fight it. I think you will have difficulty finding a discrete part which is a sub-component of the belt system.
Originally Posted by MountainLife
We are the new owners of a gently used 2017 Airstream Interstate Lounge EXT Tommy Bahama edition. We have discovered that the plastic seat belt guide to the second row captain's chair behind the driver's seat is broken. We are handy and will tackle replacing it if I can only find the part. Any help is greatly appreciated.
Don't understand how to add an image to my post. I have pictures if someone can enlighten me on how to do it. Thanks.