[amluto]

With a legacy car maker, the service centers are independent (sort of). They have phone numbers, they answer the phone, and they want your business. If your car is drivable but needs a part, you can ask them to order it, and they will do so. Tesla service centers do not answer the phone, do not answer email, and generally could not care less about you unless you have an appointment made on the app. And they do not reliably answer messages sent via app. And, while their people might notice that they don’t have a part a day or two before your appointment and tell you this (by in-app message) and advise you not to bother bringing your car in, the automated workflow part of their app does not understand this, and there is a chance that you will get stuck and your car will never get fixed.

You can bypass this process to some extent by walking into the service center without an appointment, hopefully getting a friendly person, and having them ask you to make a service appointment while you stand there (using the app on your phone) so they can then log in, find your service appointment, and attempt to get the system to let them order parts while you stand there (a process that may or may not require a tiny amount of actual technician time because, while Tesla has all kinds of telemetry, this telemetry does not integrate at all with the system by which service centers decide what parts are needed).