Sold wrong product

On the 7 June 2019 Russells was running a special on its stock. Among that stock, they had a Sansui trolley speaker selling for R399.00 ,and the normal price was around R1399.00. I bought that speaker at one their store at 2 Beatrix st Arcadia, Pretoria and arranged to collect it at their warehouse in Roslyn, Pretoria as the store did not have stock. When I arrived at the warehouse I was told they don't have stock either and they sent me back to the store. At the store they said the stock will arrive in 4 weeks time as it is ordered from China. After 4 weeks I went to the store and I was told that the speaker has been discontinued and is either they refund me or they give another speaker ,Diamond. They showed me the image and the features of the speaker and I was satisfied with it and I opted for it. To my surprise when I collect the speaker at the warehouse, it was totally different to what they shown me. It was a very small speaker ,not even a trolley. I then phoned the store to ask for clarity, and the store manager, Poly said there is nothing she can do as I have made a choice. I tried to lodge a complain with their customer services and I did not succeed.