Removing ex-partner's email for Apple Music purchases

I have successfully used my email

to add funds to my apple

account but when I want to subscribe to music they’re showing my email of my ex as the email that will pay for it not my own email. I have tried creating account with Apple but after inputting the verification code they will send to my email, it doesn’t take me to the next process it rather turns the boxes red and I have requested for verification through phone call but they didn’t respond to it. Please I need to remove my ex email so I can make purchases and subscription myself. How should I go about it please

[Re-Titled by Moderator]

Original Title: Apple Music purchase