What can i do to correct a business who is improperly crediting someone else for the slogan i made up?

I am writing a letter, please answer in a way that i can put in a letter, i'm looking for ideas. I came up with our company slogan. I recently received a letter that gave credit to another gentleman in our office for being the author of the slogan/mission statement... What is the most effective way to inform the company through a letter that they are crediting the wrong person?|||Tell them the letter seems to contain some missinformation. Then, tell them it was your idea.