"Please don’t shout"

I was visiting my mother in ward 52. In the ward it has lots of people with dementia. The ward is locked. On my first visit I was waiting to be allowed on the ward I rang the buzzer and I could see two carers standing talking. I waiting a little bit and rang it again thinking they maybe didn’t hear it. The carer opened the door and I felt she was very cheeky. She got me into trouble for ringing twice. I said I was sorry. Later on that visit I saw the same carer shouting at someone when she was giving out the hot drinks. The lady was clearly quite confused. She had asked for tea then changed her mind to coffee. The carer told the patient she wouldn't change it and suggested that she was "at it". The lady seemed very distressed.