Changed DD account details - now emailed about invalid card

[#1]

I recently started an instruction to change my accounts details from which my direct debit is paid out for fibre. Today I received an email so that "the card details saved for your broadband account aren't valid or may have expired. So that we can take the next payment for your broadband service it's important that you update your card details before 2017-10-07."

I may have paid the initial set up fees on a debit card but I've paid for everything else using direct debit on my current account so why do I need to setup new card details? The payment doesn't go via my card otherwise why have a section to enter sort code and account number?

I don't have a debit card on the current account I am switching to anyway.

[#2]

Hi there.

We've just sent that email automatically because there are no active payment details on your account.

I'd expect your direct debit instruction to activate before your next billing date so I wouldn't worry too much about that.