Who should cover warranty?

I bought a samsung phone at pep in March. Within 3 months it had problems and took it back. They advised they need to book it in for repairs. Now they said I need to pay R1500 for repairs or pay R800 for transportation fees. Don't phones have warranty? Who must now pay these fees? R4000 down the drain and I want my money. This happened at Pep Mams Mall