left goods at the till

I went to Cambridge at around 11:45 on Friday 2016.03.11 to buy washing powder. On arriving there I bought a Maq 3kg washing powder, and I also bought a Jabu stone hairspray, 1 kg brown sugar, 2 litres pine nut and sunlight laundry soap. the items came to a total of R81. when I arrived home I realised the hairspray was not in the packet. I thought it fell in the boot of the car, O Saturday I checked the boot, the spray was not there. I called the shop and found a guy called Chauke. I told him I bought the hairspray and it was not packed with the other items that I bought. He immediately told me I was wrong as it was every customer's duty to check all their items before they leave the shop, which is true. But still mistakes do happen. I didn't pack my items. And also at the exit checkpoint the securities do not verify the contents in the packets. they just stamp the receipt and you leave. what if I bought groceries of R2000. can I also check if all my items have been packed and having thrown away the receipt is there no way the shop can verify my purchase of the said day? they dismiss me as being wrong? its not about the price tag of the item, but customer service or value 4 money.