Charged for Apple Music even though I'm on an Apple One Family Plan and Apple Support will do nothing about it

Hi - has anyone had this issue? I have been on a family Apple One plan for YEARS. And have used Apple Music. I signed into Apple Music on a new device with my Apple ID (that's attached to my Apple One plan) and for some reason I was charged 10.99 for the monthly fee. When I logged in all my saved songs and playlists were there from my regular account. What's going on? My refund request for the app was denied by Apple.