Please file credit card disputes by writing a letter to the address shown on the bill for billing inquiries within 60 days of the day that the charge appears on your bills.
This process puts the credit card company on notice that, under federal law, they either have to refund your money or give you a written explanation why they won’t, within a reasonable period of time.
Filing disputes via web site, e-mail or telephone doesn’t trigger those protections. Neither does filing with the CFPB. Not saying that any of these are bad ideas, but when you send this letter they know they’re under time pressure to respond ... and they can’t reverse a decision to credit your account six months later.
The Fair Credit Billing Act was enacted in 1975, and its protections are triggered by writing a letter. E-mails and web sites didn’t exist back then.
Further details are here:
https://www.consumer.ftc.gov/articles/0219-disputing-credit-card-charges