Damaged phone accessory

I got my cellphone on a contract about 2 months ago, the charger I received with the phone was broken, I went to the store hoping the would exchange it because it's still on guarantee plus I'm not at fault. They refused to exchange my charger. I had to go through additional costs to buy another charger.

This took place at the musgrave telkom store. I do plan on taking this matter further legally, the store manager was also not cooperative.