Purchase of heater

Once again Shoprite Checkers have a bad attitude, I purchased a heater to the value of 250 and lasted 6 weeks when I took the item back with my till slip, the Manager gave me bad attitude,and said there is not stock, I then asked what do I do with the damaged goods if there is no stock, and should I now loose 250 rand which to me is a lot of money when you do not have it. I am now sitting with a broken heater which does not work. Any suggestions please. This is unfair to the customer to be treated the way I was bad attitude as though I was in the way, If us the customers do not shop at Shoprite to generate income the employees and staff would have no jobs.