Best answer by daniiiiiv
Both of these changes can be made yourself within the app or website
Please log in, go to “My Account” -> “My details” and press “Edit my details” where you can change the email address.
As with payment details, this can be done by going into “Billing” where you will see options such as “Manage my direct debit” and “change my billing method”. In the manage my direct debit, you can change your details and of course the payment date.