Unreliable service

I was supposed to receive my parcel (overnight). In the early hours, they called to confirm my address, they were at the neighbouring town. Later I called them back to confirm if they are still coming and they said they were on their way...when I called later (18:30) the courier guy said he was instructed to go back with the parcel because I'm owing. Which is a lie, I have proof of payment because I paid cash and I have no account with them. I'm very disappointed because I needed the parcel the following day of delivery. Now I had to cancel my schedule because of them.