Well it is simply reversed marketing, and as long as you previously developed teeth to chew them and spit them raw if push came to shove, success is warranted. In general, your research will send you to good people.
So, an update. When this first happened, I contacted the dealer two times with no avail: a voicemail to the service advisor, and an online comment thru the dealer website.
Getting nowhere, I wrote to MBUSA thru their website. A few days later, I got a voicemail from the service advisor, and an email from MBUSA. And I got another email from MBUSA that because I couldn't be reached, I should contact the service manager of the local dealer.
I called the service advisor, who talked to me as if his mouth was stiff from Novocaine, and asked him to leave the replacement part with the sales people since parts/service will be closed Saturday. I went to the sales people, and I waited 30 minutes as I got passed from one person to another. Finally, someone called the service manager, and he calls the service advisor, and they find the part, and I was off on my way.
It seems MBUSA has a quality assurance protocol. The service advisor obviously had to report back his contact attempt with the customer to the service manager, and so the manager must have reported back to MBUSA which then requested that I call the manager.
Overall, I was impressed with the QA, but still very unimpressed with the stiff lipped service advisor.