Very disappointed in The Courier Guy's poor service

I have used The Courier Guy many times and have been satisfied with their service up until recently. This week I was expecting a parcel and saw that it has been marked as "delivered". However, I did not receive my parcel, I was not phoned at time of "delivery", and I did not share my collection pin with anyone... which means the parcel was handed to someone without verifying they are the correct recipient. In an attempt to retrieve my parcel I have phoned The Courier Guy multiple times as well as logging an email request for assistance - I have not received any reply and no one answers the phone. Still no parcel and very disappointed.