Bad service, unworking item .

I bought an essential electric 2 burner stove on the When i reach home only one side was functional. I returned the stove and wanted a refund because i noticed that mostly their electric goods always give me a problem. When i returned the stove and asked for a refund they refused ; saying i should not have used the stove. My question was how should I have known if the stove is not working if i have not used it. I switched on the 2 plates , after some time i noticed that only one is working. They are saying i should have switched it off immediately and returned it . How? I bought the stove for cooking, i diagnosed while cooking , should i have switched it off immediately while my meal is still cooking ? They refused to give me a refund. I can't be caring their stove everyday when it's no.longer working. I just need a refund so that i get a better working brand. I was attended by a guy called Skoliwe fresh food manager abd and the branch manager. Very disappointed by how rude their branch manager was (had a tag worn upside down).