Overnight Delivery is a myth

I purchased a laptop from HP in Sandton, with the emphasis of urgency as i am in a course in Newcastle and need it for my studies and to present a slide show in 3 days time, Dawn wing was hired as the courier company and was informed about the overnight delivery, I waited until 4pm and the laptop had not been delivered, So i had called the company to find out when will it be delivered after bouncing around between the Johannesburg and Durban branches i was finally told that they do not deliver over night i have to wait 5 working days which is way too late and was told there was nothing i can do but wait. My reasoning here and the reason for my anger is that why do you advertise overnight delivery but cannot keep up to your word. So there is no integrity in your business practices. Even on their website they brag about overnight delivery. I personally feel that this company has no business ethics