The situation: Flight purchased from a travel agent (not OTA) on a non-US based airline. Transaction was an exchange of another ticket plus fare difference charged to Chase Sapphire Reserve. The charge that appeared on my statement was in the agent's name, not the airline's name. The flight was canceled by the airline prior to the date of departure, which should have entitled me to a refund. Note it was not possible to rebook (though this shouldn't matter). Tried several times to get a refund, travel agent refused any refund citing the airline's policy and the fact that the ticket was non-refundable and I could use the credit for future travel. There was basically no getting anywhere with the agent (lesson learned, I won't be giving this agent any more business in the future).

My profile: Chase credit card member for >10 years. CSR member since the card's inception. Total 2 credit cards and 2 bank accounts. $1000's in travel charged to CSR per month (pre-COVID), pay off entire balance every month. (None of this should really matter but you never know...)

The sequence of events:
1. I filed the dispute online and filled out the basic online form stating what happened. I never heard anything from Chase other than the standard "we have received your dispute" and a temporary credit. This turned out to be a mistake. I suggest calling and also sending a physical letter -- see below.
2. A month later, I received a letter stating they resolved the dispute in the merchant's favor. This letter included a copy of the merchant's response, which was a lot of nonsense and ticked off the box saying I had received the product or service, which was obviously false (the merchant claimed that the fact that I still had a credit for future flight was evidence that I had received the service). The merchant also made various other claims, like the fact that the I had exchanged another ticket meant the non-refundability of that ticket would carry over and so on, which was all irrelevant because the flight was canceled!
3. I called Chase disputes. After explaining what happened to the first phone agent, she basically answered "hmm, I'm not sure why it was resolved in the merchant's favor and not in your favor", but there was nothing she could do, so she referred me to a supervisor. After discussing with the supervisor, he agreed to "further research" the dispute, which would take 15 business days. He made no promises but suggested I fax or mail any evidence I had in my favor. During the "further research" process, I did not retain the credit for the disputed amount (i.e., I had to pay the bill and wait).
4. I sent a physical letter to Chase. The letter followed the standard FT advice of being short and factual. I simply stated what happened, and I also attached a copy of the DOT enforcement notice dated April 3, which you can download at https://www.transportation.gov/airco...nds_apr_3_2020.
5. A month later, I received a notice stating that after completing the further research they had resolved the dispute in my favor, had re-instated the credit, and the credit was now permanent.

Lessons learned:
a. Be careful when starting the dispute online. The online form has a strict character limit, so it's not easy to explain all of the facts of the case. On the flip side, the merchant's response was lengthy, which I think worked against me. It may be better to start the dispute by calling or mailing (despite the fact that they encourage you to dispute online). Regardless, see next two points.
b. Send a physical letter to Chase. After talking to the phone agents it was clear that if I wanted to send supporting information it had to be done in the mail or via fax (and their fax number was busy when I tried...). The address is below. The letter should include your account number, the merchant name, and the dollar amount being disputed.
c. Cite the DOT guidance. I obviously can't prove that this is what led them to change their mind but they did change their mind after I mailed them a copy of DOT's letter (assuming they actually read the letter it would be clear why I should have gotten a refund).
d. If the dispute is resolved in the merchant's favor, it's not over. You can ask Chase to initiate "further research" though you won't retain the temporary credit during this time.
e. All of this takes a while. My flight was originally supposed to take off over 3 months ago, right at the beginning of the whole COVID restrictions.

Chase Cardmember Services
PO Box 15299
Wilmington DE 19850

Despite my initial frustration with the process I am very happy that Chase came around. Separately, I had a good experience with Chase UR Travel (had about 300k UR refunded), and I will happily pay the AF this year despite getting little use out of the card benefits currently.

Good luck everyone.