What does \overnight delivery\" mean?"

I called Umhlanga Lazer Clinic Monday to confirm they received my deposit for one of their products, for which I paid almost R2000, which include the delivery charge. On Tuesday, 19th April I e-mailed the receptionist to ask for the courier company's details, since they sent the parcel back in January due to not finding my mail address, which I found completely unprofessional, to say the least! Last month I managed to speak to the driver to give him directions of how to find my home address, which he managed to do. Yesterday's call was for the exact same purpose, since I wanted to prevent being stood up again by Courier It, but clearly my conversation with Shireen in the customer service department was fruitless, even after I requested she give my contact number to the driver. I haven't heard a single word from them, never mind being inconvenienced and wasting my delivery money paid as part of the price of the initial product. Why must i, the customer, call to remind them how to do an overnight delivery,or teach them the importance of feedback?I find the lack of basic service appalling and substandard!