Hello and welcome to Apple Support Communities sam-r-m,
I see that you're having a billing issue and you're trying to cancel your Apple Music subscription. I understand you're concern, and I'd be happy to provide you some information to get you pointed in the right direction.
Take a look at the following article to help with canceling your subscription.
Manage your Apple Music subscription
If you should need to update your payment information, the article below can help. Any other billing questions that you may have, you'd want to reach out to Apple Support.
Change, add, or remove Apple ID payment methods
Get Support
Thank you for using Apple Support Communities.