Return or exchange required

I went to Clicks Uitenhage someday in the week of the 23rd to 27th of September to buy Sunlight auto 2kg yellow pack. I wanted pink bag auto but was given handwash 2kg by the lady that helped. I only realised that I got the wrong packet when I was opening it at home a few days later. I tried to return the packet as I did not use it and the manager refused to take it back... Is it right if it was a mistake. Please assist me. I want to exchange the product. I still have a receipt.