Suggestion: Be polite to customer service representatives.

The representative just works at the company and in all likelihood they are not at fault for whatever problem you are having. 

If you find you are getting upset, the best response is to take a breath and say something like, "I am sorry I am getting upset. I know this is not your fault and I appreciate all the help you are giving me." 

It is a quick way to deescalate yourself and if you have upset them, it also helps them to take a breath.