You are not there to be their employee and do everything for them. You need to establish that right from the start. Start as you mean to go on otherwise you will forever be their slave. 

If you are delivering 20 hours of coaching per week then you need to be doing 20 hours of coaching work and the rest of the time looking after your own business, ie: Marketing and sales activity. Whilst you are over-serving your clients, you are destroying your own business.

Coaching has taken place when there is a shift in thinking and or behaviour in the session. A transformation. Consulting is telling someone what to do and far more specific. 

You can use the teach a person to fish analogy to explain to clients. A consultant gives you a fish, so feeds you for a day. A coach teaches you how to fish so you can feed yourself for life.