Disrespectful cashier

Today I went to Clicks (Hammarsdale Junction mall). When I was at the pay point, there was a queue with one cashier working of which it was not the first time happening. Eventually Indian lady( sorry to us ethnicity to describe her. the only indian staff there) called in for two more cashiers.

The electronic thing that is used to call for next customer was pressed by a cashier(black lady with long dreadlock) of which i was next. When I got to her, she and the Indian lady were busy counting cash in cash register and I ask them why then was I call if they are still busy counting notes. The indian lady apologize and ask me to go back to queue. Instead of going back to queue I step back and waited for them to finish. Lady with dreadlock press that thing again to ask for next customer while am standing right in front of her, which I find disrespectful becouse I've been stand in front of her waiting for her to finish counting while she should be assiting me or else should have not called for customer to come to her. As I step to her to pay I ask if she's ready for me to pay or she's still need to count those notes. She reply by saying I have attitude and why do I have so much attitude. I tell her that I don't have attitude and even if I did I had a right to becouse she called for someone to come pay only to find that she's busy with something else and never bother to apologize for keeping me waiting.

I was so ****ed that she was disrespectful and she pressed that thing to call for me to pay and now am waiting and she's telling me I have attitude. That is not acceptable CLICKS. And I want to know how was this handled.