Bad service at Shoprite

I was at Shoprite Westonaria when the cashier was unprofessional and rude only when I told her I will write an email she apologized and treated us fairly but previously she was rude with an attitude not acknowledging us as customers who have been standing in que awaiting service just like everyone else... If she wanted to assist another person who was not in que she could have let us know and apologize for delay but she didn't she said with attitude am just helping him with change we asked because we been waiting in que we not important or are we not customers will she be paying for us that's why she is treating us like this