Refusal to process refund for small value item and condescending Store Manager

I purchased mouse and keyboard combination from the Nicolway store. After less than a month of use, the mouse stopped working. I took the unit back to the Nicolway store and the staff refused to process a refund, booking my unit in for repairs. It is unacceptable that such a small value item warrants a booking for repairs, a refund should be processed. When I called the Store Manager, she was very cheeky and condescending with me and asked if I still had the till-slip so that I could read the terms and conditions on the back of it.