Would be interested to hear the outcome. The letter to the client is snarky: "I’ve only been running companies for 3 years now so I don’t have nearly the experience as <redacted>, but it’s been my experience that when spending money generates more than the spend, it’s always a good idea to continue and even increase that action."

I would have briefly summarized the return on the client's money in bulleted form and omitted nearly everything else. Have you actually measured or estimated the ROI based on the improvements you stated?

Of course the letter is snarky. They cancelled a long standing contract with very little notice, no explanation and made it quite clear the decision was final. I avoid feet kissing is such situations ;-)

I do respect the strength of personality to speak your mind.

This is why I prefer to spend my time on my software biz instead of my consulting biz. Crazy I know.