Turn a irritated customer into a happy one

I was having a issue with FNB's courier company. I had already been to the Broadacres branch in the morning and asked if i can tell tell the company to deliver the card to the branch. i was told that I could. So when they called I told them exactly that. The gentleman who i spoke to listened and took down the details. Within the next 10 minutes I received a message from them stating that they have not been able to get in contact with me and so I must call them. When i did, I was already not in a \happy place"one would say. I told the lady on the phone my story and although she was being nice"