I had an odd experience. I bought 2 devices through apple. One of them went through Tmboile and the other through apple outright, both had trades.
The tmobile trade was received, they looked at the device and I got the notification that it processed. My Tmobile account was updated with the amount of the trade credit applied. I verified the credit the same day. Couple of days later I got an email from Tmoible that said the device I sent was different than quoted and they went ahead and adjusted my credit. I looked and saw the credit was now double what it was supposed to be. Thing is, they got the correct device, someone made a mistake in my favor.
After seeing this I thought they had screwed up my other device since it was more expensive. Nope, trade went through as expected. Apple credited me the full amount.
So I ended up with double credit on one. The funny thing was I was 100% sure they were going to nail me on the Tmoible trade because the screen had a small chip in it. My wife didn't tell me about it when I did the order. I sent it in figuring that I could always get it back and give it to my daughter if I didn't like the price. Ended up not mattering and getting double the credit on it somehow.
I'm grateful and surprised for the error but figured I'd share the story of my good fortune, not everyone is getting screwed.