My Apple music is saying account linked to another Apple Id

You didn't (and shouldn't have) made a new account/ID. You should have changed the email account in the old ID's settings. Here's how you change the email address (Apple ID) you use for your Apple Account while retaining everything in your account:

1. Go to https://appleid.apple.com and sign in.

2. In the Sign-In and Security section, choose Apple ID.

3. Enter the email address that you want to use as your Apple ID.

4. Choose Change Apple ID.

5. If you changed your Apple ID to a third-party email address, check your old ID email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> If you didn't receive your verification or reset email - Apple Support

6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> What to do after you change your Apple ID or password - Apple Support

For more details, read the document: "Change your Apple ID" --> Change your Apple ID - Apple Support

The subscription cannot be transferred from one account to another one.

Hi, could you logout of your newly created apple id 'samwillow90' and log back into your old apple id? If, your old apple id has worked with apple music in the past. Alternatively, change your email address on EE, then use that one on your iphone.

It depends, usually apple doesn't allow user to change their default Apple ID, but it should allow them to enter an alias email address. This is from my knowledge. I'd advise to try out Limnos message first.

Having the very same issue here. Think an old account from a good 15 years ago in Ireland is causing the problem. I'm also trying to lig in through EE as an add on to my plan. Keep going round in circles.