I am always a little leery of purchasing mil surplus. Always considered getting the 4-piece MSS. After enduring this cold spell we are just starting to emerge from here, I'm really motivated to save up for one before next winter to keep in the vehicle. Quite a few, from time to time, show up on AMZN, some "unissued", some used.
Another fine point about "unissued" is it does not necessarily mean undamaged. I saw a post recently (can't recall where/what forum) but the person received an "unissued" cot that had what looked like duct tape wrapped around one of the supports.
Based on my experiences and reports from others -- including yours -- at this point, I'll save for a few months and try to find a new or new unissued one. Hoping price may even be a little better off-season.
In your case, it sounds definitely used and was misrepresented. Curious, was the purchase source a well-known seller with a good rating?
Hopefully you can get some satisfaction through the return and I would definitely send a few critical emails to both the seller and AMZN -- after you get your refund
.