Customer ****** change at the till

I went to the shop to purchase a cooldrink and cheddar cheese.I gave cashier R101 and the total amount was R20,98.She punched R21 in her till and when I asked about my change I was told there's no proof and I wont get my money What is the shop really implying to us as customers? This is dissapointing and frustrating.I was assisted by Bonisiwe Zulu and I was told they is no proof I was ******