When I log in and navigate to "manage payment method", the bank account from which the DD is being taken is listed.
I then go to "edit bank details" then "are you the sole signatory?", select the correct option. Then a page shows to enter new account details, which I do. Then nothing changes even if checked at a later date and the DD is not set up with the new bank.
I explained all this on the phone and, as I have said, he lady took the new details and still nothing has changed.
The quick answer is - my existing bank details show and will not change.