bad service and not quality products

My sister bought popcorn machine at makro crown mine . within six month the machine has been returned to the shop and the staff there are so rude and unhelpful. i asked why don`t they explain to customers about return policy and they said that i must call head office to explain because they only sell not to explain. The sales manager was so rude that he agreed that the terms are only written and the returns department and its not their problem. the machine was fixed and four days later same problem has occurred and now they refuse to refund .how to do u buy machine for R5000 and never last ? N the store refuse to refund while their product keeps on being faulty .