How often do people "complain" when things go well? I guarantee that DJI fulfills hundreds of Care Refresh cases every month without any problems. The only ones you hear about are the problems. DJI replaced my drone in a couple weeks even though I couldn't recover it (fell into a river). I was decent on the phone to them and sent logs with footage to back up my story. No problem. I also had State Farm, unfortunately I lost a 3DR Solo and State Farm will no longer insure me for a drone. One and done.
For all DJI knows, this guy found a broken Mavic somewhere and is trying to scam them. I'm sure that it happens. On a teachable moment note, I hope everyone has their serial numbers recorded and doesn't rely on a manufacturer/retailer to keep track of them for you. When I received my replacement, I took the steps to ensure my new drone was registered correctly. Not because "DJI customer service sucks" or whatever but because I'm an adult. Your Care Refresh contract is readily accessible in your DJI account. I suggest everyone takes a moment to make sure that you've recorded your numbers correctly.
As far as advice goes, if this is truly what happened, I'd have to go along with others here that suggest you call back calmly, when you have plenty of time and ask for a supervisor. I'm still kind of confused how this happened since they get all of the info from you before they have you send it to them, don't they? I admit to not being sure since I didn't have a drone to send back. The other thing that strikes me is your statement that you're out the transmitter as well, considering that they sent me a drone only with one battery and props.