Requested overnight delivery

Good day <br> I requested an overnight delivery on a package from east London. It was an urgent delivery. There was no sign of the parcel and when I called the call centre to find out what had happened, they advised they would call me back. I have not received a call from them, no one seems to want to assist me, and this package was urgent. When I tracked my parcel it says delivery exception and no-one seems to know what that really means. I find post nets service extremely unreliable as a phone call could have been made to inform me of such. I need the package by tomorrow failing such I want a refund on my package as it would not be needed.