subscription is being used by a different apple id

That message as you state it doesn't make sense. Is that what it says exactly? A subscription is associated with an Apple ID, it can't be used by another ID unless it is a family level subscription in which case it can be shared and shouldn't produce that message. Or did you change your Apple ID or password before this message in which case please click on this link and read "What to do after [or before] you change your Apple ID [email address] or password" --> https://support.apple.com/HT204071 - "After you change your Apple ID email address or password, you might need to update your sign-in information with any Apple services you're using."

Got me on this one. Are you subscribed through Verizon?

Contact Apple and ask them. When you find out please post back so I know how to help the next person with this issue.

Click here --> https://support.apple.com/choose-country-region Select your country, then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.

or:

Contact Apple for support and service --> "See a list of Apple phone numbers around the world."

Click here --> https://support.apple.com/HT201232