Trying to resolve Apple Music subscription issue

Here is the link to Contact Apple. If phone support is not available in your region, try the Online Support.

Contact Apple Support - Apple Support

Here is the Support Article from Apple for connecting Apple subscriptions through a cellular provider:

Connect Apple subscriptions from your wireless carrier or other provider to your Apple Account - Apple Support (NG)

And the MTN website with FAQ's for questions such as yours for connecting Apple Music.

https://play.mtn.ng/apple-music

If you are getting the runaround or Apple cannot resolve the issue, don't forget you are paying MTN for the service and they are responsible for linking your payment to your Apple Account and managing your subscription. They do this usually with a SMS message and the support article above says if you don't have your account linked and unresolved with their phone support, then visit your local MTN Store. If still unresolved, I would cancel the service through MTN that is unusable and make that subscription directly with Apple using a different payment method, which you can find here. That way it is Apple that is managing the subscription instead of MTN:

Payment methods that you can use with your Apple Account - Apple Support (NG)

Contact MTN. That is a common issue where they have to link your subscription that was enabled through MTN to your Apple Account. Users who contacted MTN got their issue resolved. Apple has no access to your MTN account, so they cannot do that.

I’ve actually contacted MTN about this issue multiple times over time, but unfortunately, it still hasn’t been resolved. They have now advised me to contact Apple Music Support directly for further assistance as MTN has been unable to resolve the issue on their end.