Credit Card Liability

[FernSam]

My husband had a credit card account in his sole name. There was a second card issued to me as a second cardholder. There is a monthly direct debit set up in my personal bank account to pay the balance of the credit card. The credit card company were notified of his death eight days prior to them debiting my bank account. They've written to me stating the final balance of the credit card and requesting updates regarding his sole estate as I'm executor. He has no sole estate, everything he held we held jointly. I understood that having been notified of his death they would by law have to cancel direct debits associated with that account. Can I cancel the direct debit to pay the final balance? What is my liability if the account was in his sole name please?