Is the executor responsible for payment of any bills accrued in the deceased name until probate.?

My grandmother purchased vehicles for her great-grandchildren before she passed. The executor was contacted by both banks on several occasions to fax or mail permission to refinance the vehicles in their names in order to avoid repossession. However, she disregarded the messages left on her voice mails and emails resulting in one of the vehicles being repossessed. The banks would not allow payments or information because of this purposeful lack of communication.