Does a new cd transport require break-in time?

......I waited a week. No indication of them sending me anything. I called and they said there was no evidence I had sent it, even though I followed their instructions implicitly,
By this time they had received my unit......

When you send something Fedex, regardless of the entity paying for the shipment, *you* immediately receive a receipt with the tracking number that you can (and should) use to track the package. Point is you would know whether or not they received it.

Here is something else to do now, as I’m about to "pull a string" here on your behalf. Send an email directly to Jason Stoddard describing your situation *and fedex number*. Email him at at [email protected]. Then, kindly report back here (as you have already been doing) as to whether or not you are getting the service you expect and deserve.

Unfortunately, I have no record of the serial number.

Also, I was tracking the package with the number I got at the FedEx office, and it got to Schiit the day it said it would.

I wasn’t supposed to send a tracking number.  All I was supposed to do was paste the label they sent me onto the package.
Evidently there was a tracking number on that label that would have started the return process.
 FedEx probably covered the label with their own and assigned a different tracking number that Schiit had no knowledge of.