Dear (employee name),
A number of your work associates at (department name) informed me of the (date) incident (quick description of incident). This situation involved (company name representative).
When we contacted (company name), management agreed that their representative was extremely abusive to you and used coarse and unacceptable language. The management team at (company name) agreed that (company representative name) was behaving in an offensive way.
(Company name) representatives also let me know that throughout the whole altercation, you remained civil and calm. You were always trying to get to the bottom of the problem and come up with a satisfactory solution.
I’m writing this to compliment you for your professionalism and self-control. You handled the situation the right way. In fact, the way you carried yourself was nothing short of exemplary.
I have already called (company name)’s owner and I’m confident that you will soon be getting a direct apology from them.