@notmyname There are two things I want to correct about what you said:
1) The card was not activated the same day that someone else had it. It was activated in mid-May and then used in early June, meaning something happened to it during the time between those dates.
2) I closed the accounts because I wanted to close them after thinking it through, not as a knee-jerk reaction. I still think Chase is a good company overall, but my own relationship with Chase was no longer good once they started accusing me of lying (and presumably also flagged me as a problem customer).
On the rest, I can't deny that the circumstances are confusing.
I can't speak to how to resolve this but I can attest to CHASE making some crazy bone headed decisions that lead a customer to immediately terminate their relationship with the bank. About a decade ago I had a significant sum deposited there and a debit card fraudulent transaction. I disputed it and they initially credited it back. Over a month later the transaction was processed again and CHASE had the same claim that I had done business with the woman. I had no relationship and had never requested any transaction but that wasn't enough for CHASE. I didn't know about a police report or FACTA and had to swallow it. What pushed me to terminate my banking relationship with them was when the guy on the phone in the fraud department had the audacity to tell me that the money I had on deposit with them was THEIR money and they allowed me to use it. **bleep**??? I hung up and after scraping my face off the carpet jumped in the car to my local branch and closed 2 credit cards, checking, savings and a 401k. The local banking officers begged me not to and apologized. They got the fraud department on the phone and the twatwaffle even restated it was "their money and I was allowed to use it" again. I took my funds and left.
I don't know why CHASE has done this to you all I know is they do some strange stupid stuff and once locked in won't back down. They do not care what you think of them. Good luck.
I realize this topic has been talked to death, and there's no need for a lengthy continuation at this point. I just wanted to provide a quick update: After yet another investigation by Chase, for which they were provided the security camera pictures and other relevant materials, the finding was still the same, with no explanation other than that they determined the charge to be "valid." I have paid the amount that was due and am taking this as a lesson that a wallet needs to be checked for the presence or absence of all cards on a fairly regular basis. Thanks again to everyone who offered their input earlier.
Thank you for the update. Very sorry to hear Chase is still sticking with their initial take. Unfortunately, it seems like another case where the initial investigator screwed up and the later investigators started out with a strong bias toward reaffirming the initial conclusion.
As you correctly noted, this kind of awful customer service is definitely unusual from Chase. But, obviously, no issuer is perfect. Even still, it's 100% understandable that you would no longer want to do business with Chase going forward. I would feel the same way in your shoes. It's one thing to know, intellectually, that any issuer could, one day, give you the shaft; it's a totally different thing to actually get the shaft from a specific issuer and then choose to keep doing business with them. The fact that Wells Fargo, or AmEx, or Citi, or Comenity, or Synchrony might have hypothetically responded to this issue equally as badly, doesn't change the fact that Chase actually handled the issue this badly.
I guess the biggest takeaway here for all of us is - keep an eagle eye on our cards, and lock cards as soon as they go missing.
Also, personally, this reaffirms my longstanding hesitance to retain rarely-used cards. Much easier to notice a missing card if you only have 5 or 6 cards in the ol' billfold!