Retruning broken products

On 6 June i went to exchange an AIM dvd player that i bought during May 2015, because the remote was not working. I was assisted by a rude person in the electronic department, after a fight because didn't want to help me. He eventually took a new remote from a sealed box, then put my broken the remote in that box and placed it back on the shelve. On 21 June I returned a Verimark vacuum cleaner as it is broken. The staff was very unhelpful and discussed me in their own language, infront of me thinking I would not notice. I left there with my broken vacuum cleaner, which is only 3 months old, because I was refused any assistance in exchanging the product. I now paid R800 for a product that is not working and I am being refused a new product. I don't want the Verimark vacuum cleaner again, as another one will just also break. I wanted to exchange it for a different make of the same price, but was refused. This is unacceptable!!!!!