Continuously postponing delivery

I am beyond frustrated. My parcel keeps saying out for delivery and never gets delivered. I have contacted them, and I was assured it would be rectified today, only to be disappointed once again. I have received no phone calls or communication stating that there will be a delay or that they will not be able to make delivery. It is a battle to finally get hold of a live chat agent, and I'm always the one reaching out. Absolutely the worst experience I've ever had with a courier.