You fucked up. You're screwed. In hindsight, you should have insisted on a 100% refund in February 2021, followed by a rebill in May 2021 after you received the product. That did not happen. Instead, you just agreed to accept deferred billing beginning in May 2021. You still had to pay the balance in full by January 2023 to avoid retroactive finance charges. According to your post, they never said they would reset your promo period (and, why should they, if their money was outstanding from February 2021?). Unfortunately, you misunderstood what you were getting. Synchrony and CareCredit are predators, so they are not going to do anything for you out of a sense of doing the right thing. There whole idea behind deferred interest charges is to ensnare people like you, as opposed to normal 0% APR promotional financing, that does not bill retroactively if the balance is not paid in full by the end of the promotional period. Since you never received a refund, your balance has been outstanding, and your 24 month deferred interest period began, in February 2021. No one is going to be able to help you here. File it under lessons learned. More on reddit.com

I’m not sure what you’re referring to by horror stories, but I’ve had a CareCredit card for several years and have had no issues. I always get the 0% interest when paid in X months, which is great. They don’t have the most responsive customer service, but other than that it’s been totally fine. More on reddit.com

If you're in a promotional period, you may not owe any money monthly but interest is accruing and at some point, it's all going to come crashing down. You should log into your account and see what's on there... More on reddit.com

It’s better to pay off the closed account asap. The account will state “closed by credit grantor” but it is my understanding that this remark and closing it yourself would have no different impact on your score, though if a lender pulls your report (such as for a mortgage) they may inquire as to why the credit grantor closed your account. Accounts are closed due to inactivity, changes in the market regarding credit, etc all the time. It’s not a huge deal. What’s likely hurting your score is the utilization on the account. You see, your account now has a $0 credit limit but is displaying a current balance. That is no bueno. More on reddit.com