Unfair treatment

On the 19th of this month I visited game store in Vincent east london, I bought a hisense fridge and defy hob and oven, now the procedure at game stores is that you get a shop assistant of that particular dept and he or she helps you, you point out what you want then the shop assistant then takes down the sku/ serial number of the product and loads it on the computer then makes a print out for you to go pay at the cashier. Now after I pointed out what I want the assistant then said I must go que so long at the cashier and that he will bring my printout for me to pay. I the. Proceeded to the cashier and qued and after about 5min he brought the printout and I paid and was given the Adress or location of game storage wearhouse where I should collect my stuff. The following day I collected my stuff and too them home sealed in their boxes. Yesterday only I opened up the boxes as I was about to fit the items in my kitchen and found out that I was given the rong stove. I foned game vincent and spoke to the floor manager which was a colourd guy ( forgot his name) after giving him the details on the slip he told me that the shop assistant gave me the rong stove and he might have made a mistake. I was then told that the stove I want is costing an extra R1600 and that I must pay the difference and I will get the stove. Now the first problem I have in this matter is that I must pay extra monies for a mistake that store made themselves. When I tried to explain that I was told that it might be I pointed out the rong stove to the assistant. I then said to make it easy we can go check camera footage whereby they will clearly see me pointing out the stove I want and then also the shop assistant also acknowledged and then sends me off to the cashier. After requesting that I was told that there is no cameras in that dept and they can't help me with that. Can I pls get assistance in this matter as game vincent is not wanting to own up to their mistake they did.