Cheated by Vodacom

I was given a Samsung Tab A and I was told that if it gives me technical problems within 7 days i must bring it back and they will swap it but to my surprise the tablet never worked and when i took it back within two days i was taken from pillar to post and to top it all the humilated me as if they did not sell me the Tab A cash so it is clear that they knew that it wont work and because i bought it for cash they can just cheat me. the supervisor Dannis was the one who was there when i bought the tablet and the manager (Callie Jacob) who was called on the phone was just rude because he even dropped the phone on my ear and clearly showed me that he undermines the fact that I'm African (******) i have cheated of my money by vodacom