Access what your mid-level manager's needs really are and customize the following training solution to their requirements.
When you do such trainings keep in mind it's not what is important according to you about business communications,
rather it is what skill enhancements they would require to meet their current work-relationship challenges, team challenges etc..
These may start with Verbal communication and strategies of doing so. (See links below)
You may then move to Non-verbal communication. If you are the trainer remember to give contextual examples from the daily business routine.
I could suggest a lot but the reality of the situation is being in the environment in which your corporate culture works
you know better about what you need to deliver, close and move forward.
Take a look at these PPT's in the on-going Communication Series I maintain.
Take what is relevant. It should hold good to run an entire one day session.
Also see this link for more Managerial Skills PPT, it maybe worth your time.
Managerial Skills Series
9th May 2014 From India, Mumbai