The facts of this case:
1. July 2019 -- bought and paid thru Expedia, a one way flight on
American Airlines HKG/LAX for US$800, for travel May 2020
2. AA notified me on 12 March 2020 cancellation of flight with full cash refund, and confirmed on 21 April that refund had been processed and sent to Expedia
3. Expedia on 13 April wrote me and said that as I "wanted to cancel the AA flight that they (Expedia) has cancelled and that per AA policy, I am entitled to a voucher credit for US$800 for future travel only HKG/LAX". I replied saying Expedia's assertion is incorrect in that not me that cancelled, but AA cancelled, and I requested cash refund to my M/C card. Since then Expedia has not replied.

I am considering:
a. Asking bank that issued my M/C to do a chargeback, but payment (July 2019) is more than 60 days from my request, which I understand is the limit for requesting a chargeback. Is this 60 days limit universal (US only) or applies to all banks (bank is in Hong Kong)?
b. Filing a claim under my annual travel insurance policy for flight cancellation due to factors beyond my control, but not sure of outcome, and also for theft since once AA confirmed refund made, the cash refund now is my property. To do so, I would need to file a police report in Hong Kong against Expedia domiciled in Singapore, per their receipt of payment. A police report has to accompany any claim for loss under the travel insurance policy.
c. File a complaint to US DOT against American Airlines for not processing the refund to me, but to Expedia. American claims the fare is a "bulk fare" and that purchase is from Expedia and therefore refund should be from Expedia. AA of course has all details of this booking, ie my name, email, amount of purchase, booking record, etc. I have had a lot of transactions with Expedia in past (flights/hotels bookings) and have not had any issues with Expedia in past, until now.

Can anyone advise me further what I should do? I have documents of all of the above actions/communications, etc.

Thanks in advance.