Hello Sarahkeen,
It sounds like you have some questions on Apple Music subscriptions. We will be happy to help.
It sounds like you have a promotion that is bundled with your phone service. Is that correct?
If so, you can sign up for an individual subscription using the same Apple ID that you previously used with Apple Music. If you need help unlinking your account, contact your carrier.
Join Apple Music on your iPhone, iPad, iPod touch, Mac, or PC
Once the subscription is upgraded, your music should still be available.
Cheers!