Caller: The business owner - at my workplace

Just letting you know your abusive behaviour to me today had me in tears on the way home. I'm a person too, just trying to do my job. I don't normally let people like you get to me, but you caught me during a time when I'm going through all sorts of personal issues that are just bubbling under the surface while I go to work every day to speak to people like you.
Maybe next time you call my company and I answer the phone, remember that there are people like me who are the gatekeepers and have absolutely no idea of the problem you are having; all we want to do is transfer your call to the right department. You had absolutely no right to speak to me the way you did today. We are not out to get you, we are not out to deliberately make your life difficult. We are human beings with thoughts and feelings just like you.
Please remember this next time you call.
And thanks for putting the icing on the cake of what was already a terrible day. Much appreciated.