False advertising

I bought a phone less than 2 hours ago. A Samsung A2 on display it is a combo with a free memory card 16gig. When i told the casher Yoliswa she said at the cellphone department they say its just an ad it actually doesnt go with the memory card and they refused to give me. Meaning it isnt a mistake for them to have the ad on display its false advertising. They refused to give me my memory card