Takealot .com delivery times quoted unacceptable - need to be more accurate

Excellent shopping experience. The only problem that I have is with their deliveries. They advise that delivery would be made on a certain day before 5pm. I was away one day intending to be home well before 5pm only to receive a phone call at 1h00 that my delivery was at my house. This was most inconvenient as I now had to cancel what I was doing and rush home to receive my parcel. Why can they not give a 2-hour window during which period they will deliver. No-one can sit at home all day not knowing when their parcel will arrive.