OVERNIGHT COURIER SERVICE FAILS

I paid for an overnight courier service for an urgent part to be delivered on Monday. Yesterday I phoned as no part was delivered around 12pm. I was advised that I will only receive my part on Wednesday and that a supervisor will give me a call. What is the point of paying overnight if you receive your parcel 2 days later??? Pathetic I would say. What happened to service? This is unacceptable. I would like a full refund as I paid for a service that was not delivered.