Midas refused to exchange my car battery

Last year mid April I bought my car battery at Midas Spares Paledi mall in Mankweng, yesterday my car couldn't start as the weather was cold and raining, I had to ask my friend to jump start the car. I then drove straight to Midas return the battery as it's still under warranty, guess what the cashier refused to exchange the battery. His excuse was that the positive terminal of the battery is scratched and his supplier won't take it back. I left the store with a sad face. I need help to return this battery as I don't have another R1500 to spend. Midas will you please keep your promises that you made when I bought this battery because now I feel *******.