The body shop that repairs my Model 3 after being hit, was supposed to be "Tesla Certified" specialists too, yet they did a terrible job. Even Tesla Service Center warranty work has been less than perfect. So I have a hard time trusting someone else working on my car. I really wish Tesla had not used soft interior door materials.
I'm sorry you had a bad experience with Tesla service.
However, that wasn't my point, and I apologize for not being more clear in my post.
There are vinyl repair subcontractors who work for dealerships...primarily repairing used cars the dealerships intend to sell. These guys have mobile repair businesses, so they will go to the job (your house for example). Often, the best way to identify a good repairman is to ask used car managers who they often use. If they recommend someone, you can be pretty certain their work is excellent as the dealership doesn't want a bad experience coming back on them.
You can also sometimes get referrals from other subcontractors who do mobile work for dealerships: wheel repair specialists, paintless dent repair specialists, bumper repair specialists. Sometimes these technicians know of other highly regarded repairmen in complementary specialities...like vinyl repair.
You might also ask boating dealerships, if you're in an area where boats are common.
Finally, you can try a web search for vinyl/leather repair, but the results might not be as satisfactory as a personal referral.
Hope that helps.