Return of appliance still within warranty period

My elderly father purchased a kettle from Shoprite/Woodstock,Western Cape last year November. He kept the box and the receipt,as this was his proof of purchase. The kettle broke before the warranty expired and he returned it to the store,only to be told that the warranty did not cover the breakage. The matter was escalated, resulting in the broken kettle being replaced with a new one WITHOUT a replacement receipt. My father was then told that the kettle he returned with the slip had been THROWN AWAY. My question then,does the new replacement not carry a new warranty? The manager on duty was very dismissive and refused to give my father a receipt. A response to the above would be appreciated.