Merchant refund process has stretch on nearly 60 days and my chargeback window is closing

I ordered some sporting equipment back in February. I ordered several sizes and intended to return the sizes that didn’t fit. Upon submitting the RMA request, they said that they are experiencing a 30 day processing time (just to approve the return). I finally received authorization, and promptly mailed them back. Upon receiving the item, I got an email stating it will take another 30 days to process and issue a credit. I’m now approaching the 60 day limit for filing a chargeback, and I can’t get in touch with the retailer (no phone number or chat, email returns an automated message stating 10 to 30 day response time). I don’t anticipate having to file a chargeback, unless I never receive a refund. But at that point, my window will be closed. For reference, the refund amount is approximately $1,000. What would you do?