Pause payment pending receipt of a death certificate

My father (the account holder) has died and we want to close his account. There is currently a backlog, meaning that we have been unable to find out when we can expect to collect the death certificate. I’m wondering how we ‘notify’ his death so that payment can be paused pending receipt of the death certificate - your own guidance seems to suggest this is possible (see quote below), but I can only find the address to send the copy of the death certificate to, not anything about how to notify you of his death before we have received the certificate.

“Once we receive notification that the account holder has passed away, we’ll put any collection of money on hold for 21 days. Once we receive the death certificate and process this evidence, we will disconnect the account and de-activate the direct debit within 72 hours.”