PostNet SA overnight courier service takes more than 2 days but I paid extra for it

I paid for an overnight courier service for the shipping of a very important document to Pietermaritzburg from Pretoria at around 13:00 yesterday (13 March 2023) and I am writing this review on 14 March 2023 at 21:30 but as at close of business day the documents were not received by the recipient, What is a meaning of overnight if it takes more than 72 hours and the places are 6 hours drive apart?

The fact that I chose overnight instead of the normal courier service means the parcel had to be delivered urgently.