Exchange of faulty appliance bought on sale

I bought appliances on the 4th August 2020 on the 50% sale. Among said appliances was a Safeway blender which died on me the first day I started using it.

When I went to exhange at Clicks Manzini (Swaziland) on 18th August 2020, I was told they wouldn't exchange the blender for me unless I top up some money (E194) because it is now 1 item, hence i get only 20% discount. I eventually left the blender and took a refund.

Is this a Clicks policy? Am I not supposed to exchange a faulty appliance at the same price I bought it?

I am very upset.