Wrong advertisment and rude cashier/ manager

I went to Jet Prieska, Northern Cape today to buy the samsung A2 core todat that they have on special for black friday on adverts they show its 16gig bit when i bought it and it was only 8 gig i then told the cashier believed to be the manager aswell that this 8 gig is not the ons advertise, he were very rude and gone off on me for saying so, he would not listen to what i have to explain so i said he can give my money back, he were swaering at me and were so rude i will never shop there again and i will recomend all my friend to so the same as this is not the first time he treats customers rudely. I would like to know how do Jes advertise a 16gig and give cuatomers a 8 gig. That is wrong.