I have a question about a photograph of mine being used by a major political campaign. This photo has apparently been used for two-years on website and on thousands of mailers. I have asked in the past for them to stop using it, but they haven’t.

So I am sending a bill. I was going to charge by number of mailers, but have no idea how many they have printed and they probably won’t tell me. My question is, what is a fair way and fee to charge for this usage. And this is the correct thing to do on my part. Thanks for any help.