Depending on the size of your business, you may need to rely on customer service representatives to manage customer concerns. When this happens you cannot always be sure that the management techniques or personality of these representatives reflect your values.
You do the best you can to screen your representatives, but if they have a bad day and take that out on one of your customers, what can you do?
It may happen that one of your customer service representatives acts inappropriately or unprofessionally towards a customer. If this happens and you find out via the customer or online feedback, you must tackle the situation as you did in #1 and #2.
Do NOT excuse the actions of your representative and ensure that the representative in question is reprimanded or when severe infractions occur, released from your employment.