Unacceptable service

Over this festive season I am very unhappy with the service. I paid for overnight shipping on 2 December and my client still hasn't received their parcel today (3 December). According to the call center she might not get it tomorrow either as there will not be trucks going out. This is unacceptable. Aren't they supposed to be more productive over the festive season? I paid for overnight courier service and I expect overnight delivery