Sorry to hear that some of you are having problems with chargebacks/disputes.
I had a cancellation from Avianca in April - after about 5 weeks of “your refund is being processed” I filed the dispute with my card - Discover.
They immediately posted a temporary credit to my account and - about 3 weeks later - said that Avianca had not contested the credit and closed the dispute in my favor.
I have another dispute in process — Iberia/Priceline and a Chase card — that is not going as smoothly. I’d suggest finding a phone number for the “disputes office” and trying to explain the issue to a real person (with some authority for disputes, not just customer service).
The previous poster is correct - make sure to have lots of documentation available.
Good luck!
Bill