Joining Apple One but I already paid Apple+ TV
I have paid for a year of Apple TV (through 10/2023). Will I get credit for that, either in refund or paying future months of Apple One?
You will have to talk to the Support staff about annual plans turning over into a bundle subscription with monthly payment, before the billing period is over.
Contact Apple for support and service (phone numbers) or start your support request online (chat/email/callback).