Game Greenstone ******

I bought a generator from Game store in Greenstone mall , in 5days it stopped working, I took it back they kept it for 3 weeks, after collecting it again same problem occurred , instead of them giving me a new generator they are saying I must pay for them to fix it , where is the warranty, why are they making me run around, I'm loosing big time as I'm expected to hire the generator, can someone explain to me why the process is delaying , and why are they selling us demaged goods