Bad customer service

Yesterday I went to Woolworths in sunlam centre in Parrow. I received discount voucher by text. I went to pay at customer service . I showed the lady my voucher on the phone , she asked me to download app so that she can scan the voucher and I must wait on the side, she cancel my items and ask some customers. I download the app I showed her then I asked her why do I need to have a app for this ? I always get discount vouchers but they punch in the number? She didn't reply. Because of network then she couldn't use app then she started punching in the number that was on my text. She didn't apologize and she was having attitude. I called the manager and reported that incident and she advised me , she will speak to her .