That's what it sounds like to me - hoping you'll just give up.
I would do a chargeback. They were informed that you received an item you did not order or want (whether it was human error or some sort of website error is neither here nor there), and they are still standing by "final sale" and dancing around your perfectly reasonable request to SEND BACK A BAG YOU DID NOT ORDER?! Absolutely not. After this long, a chargeback is in order. They have had ample time to fix this and have not.
That just boils my blood. Plenty of places with a "no returns" policy will make an exception if they sent you the obviously wrong item.
I had thought about buying from them before, but definitely will not ever now! What a nightmare.