How to change bank details?

Trying to set up the current direct debit to a new bank account, but not sure how to do that.

Im a new customer (as of late September) Tried logging into the site to see if I can change payment details and such on there, as it seems like the most obvious solution, however I can’t even log in. Says “credentials do not match”. Perhaps I’m putting in the wrong password, I think to myself. Goes to reset it but never get an email to do so (I’ve been trying this every now and then for the past month now). So I try to make a new account instead, thinking that it must be the wrong email. I used the same email “this account already exists”.
I’m in some annoying loop. Can’t login as I don’t exist, can’t create new account as I already exist.
All I want to do is pay my monthly bill using a different bank account sigh

Hi Courtney!

Sorry you’re having problems, if you drop an email
To [email protected] - we’ll get you sorted out.

Yayzi Customer Support