Item marked as delivered, never received after a days delay

Paid extra for next day delivery (for Sat 31 Jul 2021), order delayed by 2 days (to Mon 2 Aug 2021) with no refund offer for next day delivery already paid. I used the app to bring the rescheduled delivery a day forward (Sun 1 Aug 2021), and the app then marked the item as delivered on Sunday, while never actually being delivered!