Poor Customer Service

I went to the store to buy one energy drink (play) as I was going to pay for it at the tills I then realised that the ques were very long especially for 1 small item. I then went to the other one for small items on the other side of main tills. As I was approaching I realised that there were people there as well about 12 customers waiting and at the back of my head I just thought it was a que for Lotto and I joined the que. I only realised when I was at the que that those people were also buying small items like me and they were waiting because there was only one cashier there. I waited as well and after about 18 minutes waiting I then approached the same cashier (Memoria) trying to establish if there was someone else that can assist her since the que was just stagnant and some of us were at work, we only wanted to pop in quickly and get whatever we wanted quickly. She then started being emotional as I asked, and mind you, I was very professional, respectful and calm when I asked or approached her