EXTREMELY BAD SERVICE

My wife bought a gas stove at Beares in Mdantsane city mall on account in May,since then,the stove has never worked,we contacted them since May,they only came last week to fetch it for repairs,now they don't want to give us a new stove they say they will fix this one,my question is why must I pay what I didn't use instead of them giving us a new stove. The sales lady my wife reported this to her today said my wife must contact client care