Wow, I’m really sorry you went through that but it makes me want to suggest using something like privacy.com for future subscriptions and purchases. You can create virtual cards that you can make merchant locked(so if a scammer got the number, they couldn’t run it), one-time use, and with a total or monthly limit. In this case, you could have simply paused or canceled the card you used for of as you were being told you needed to write a letter. I’ve used it for years in this manner and I’ve never paid a dime for the service, their free tier provides everything I need.