Selling of poor quality products

I bought a Samsung Z2 at the MTN shop at the Workshop in Durban last week. The phone already has an icon for whatsapp but when I tried to load it gives an error message that the date and time on it is inaccurate. That is surprising because the date and time on it was automatically set, I didn't set it. When I took it back to the MTN store where I bought it they seemed to know that this type of phone has problems, they tried to help but to avail. I am now sitting with a phone that does not serve the purpose for which I bought it. It was my first time buying a Samsung phone and I don't think I'll ever buy a Samsung product again. It was a disappointment.