Gamefly Unwilling to return purchased game, sent to them in error. Internet

I had been a member of gamefly for several years, In good standing, and had been overall fairly happy, other than the length of time games take to receive.

That all changed fairly recently.  I had a month or two ago purchased a copy of Skyrim for Xbox 360. They shipped me the box for it and all other applicable items.

Then a week or two ago, when I had two games from them, Prototype and Tom Clancy's Future Soldier both for 360, I shipped them back in order to receive new games.

Unfortunately I had accidentally put in my copy of Skyrim in the sleeve for Future Soldier.  At this point gamefly "assumed" that I must have wanted to return to them the game that I had purchased, and still had the box and everything else for.  So they processed the game back into their system, and I recieved an email telling me I got a whole 5 dollar refund (because of the THIRTY FIVE DOLLAR restocking fee).

Why would they take the massive leap and assume that I would return my game that I purchased just 2 months before, without any of the boxes, and be satisfied with getting 1/6th or less than what I paid for it back?  Nevertheless, they did.

I sent a couple of emails to their support, and got back responses saying basically that the game was now theirs again, and if I wanted I could buy it again.  I called the company, and they said that they had sent out the game to other members, and could not ship me another copy.  They did then give me a full refund, which I will use to buy the game elsewhere if I want it again.

I still feel like they basically stole the game from me, and refused to give it back.  I am curious what happens if someone were to send a game that they bought elsewhere to gamefly on accident, would they keep that as well?

At this point even with the refund, I am considering legal action, as well as cancelling my account.

Very unhappy, I feel like I was stolen from by Gamefly.  It was my mistake to send it, the first time I've done that in over 4 years of being a customer, but the lack of any system to confirm if I meant to send the game back for a refund, and the simply processing of it without my consent, combined with the unwillingness to simply send me a replacement copy, makes me want to cry from the hilltops for people to stay away from this company.