Nando's Calton centre service is bad

I went to Nando in Calton centre and I must say the service I got from one on their staff member was bad, when I was called to order my food I was serviced by a lady called Zakhona she did not have a smile on her face she did not even greet me to make things worse when I was done with placing my order and she had to give me my order slip she turned her back on me and I had to even tell her to face me when she was giving me order slip. When I thought that was the pinnacle of the bad service and nothing would top that, when my order was brought to my table it did not come with the juice that I ordered so I waited for few minutes only to see if my juice will come dololo. So I called one of the staff to ask about my juice only to find out I was helped by the same women Zakhona and she did bring my juice and I asked for a glass and when she brought the glass the glass was dirty and it had dirty stains on the outside. I have no problem with Nando Calton centre as a whole I just wish they teach their staff members about customer service.