Asking the customer to calm down

Telling someone to calm down does not work, the colleague should’ve given an empathetic response such as “I understand why you are frustrated but we appreciate your patience whilst we serve the other customers, we will serve you as soon as possible”.

Displaying negative body language such as eye rolling, sighing and shrugging

The negative body language has made the colleague appear disinterested and bored. The colleague should have used positive body language and kept their facial expressions neutral.

Telling the customer why the pharmacist is busy

As long as confidentiality isn’t breached this isn’t an issue. However, this sounds like an excuse which the customer may not be interested in. Also it may take more time to explain the issues rather than simply getting on with the task in hand.

Raising their voice/shouting

The colleague should have stayed calm and managed their emotions

Being sarcastic

The colleague should display professional behaviour and be polite to customers

Telling the customer the wait is another 30 mins

This may help the customer plan their time but it should be as accurate as possible.