Bad or defect product

I purchased a Bluetooth speaker 10 March from the shop in Durban. I live in Richards Bay. The lady on the floor played the speaker a demo model on the floor and we were very happy with the sound. So we took one in a sealed box. When we played it at home the sound was horrible and blurry so I had to send It back with a courier service which costed me R140. The lady at you store told me they have to get the Polaroid company out to come and look at the speaker. So I need to wait another 10 working day to get a new speaker. She received the speaker today 15 March. I need to ask you how is this fair. No my money is tied up because of a bad product and I went there with the intention to get a quality speaker/