No service & No delivery

Why have an option for overnight delivery when your parcel has not been delivered two days later. I sent a parcel on 12/12/17 from Port Edward to Selcourt and specifically asked that it be sent with overnight delivery as the person who needs to originally sign a document is going on leave the next day (13/12/17). On 13/12/17 I phoned the postnet call centre and was told someone would phone me back shortly (which of course did not happen), I again phoned on 14/12/17 as the person came in the morning and was again told that someone would phone me back which again did not happen!!!! The document which was sent was a refund form which deadline for submission is the end of December so due to postnet's failure to deliver and HORRIBLE SERVICE I will not be receiving that refund and it cost me R185.00 to send an overnight parcel (which was not delivered overnight). I will make a point of NEVER using postnet again!!!!