Know-How Exchange : Copywriting

You might try Communication Fitness. They have a pretty wide range of services that includes business communication at various levels.

Full disclosure: I have been involved with Comfit on-and-off over the years in a consulting capacity. I believe they have a very good product overall, but I can't speak with first hand knowledge about your specific request.

Your best bet will be to ask them. If they can't help you, they can probably recommend someone who can. The president there, Barry Tarshis, has helped hundreds, if not thousands, of business professionals with communication issues. I'd be very surprised if C-level tone isn't among their capabilities.

You might try this Business Writing That Counts:

https://www.businesswritingthatcounts.com/


They offer online self-study courses, webinars, and workshops.