Cancelled Coaching Sessions

I am using volunteers for coaching sessions for CCP. So far I have remained flexible in times available and trying to work with peoples schedules who want coaching. I rearrange my schedule so I’m available to them. I have had people cancel last minute, be wish washy on scheduling and following through. I’m getting really irritated. I feel stuck because I need sessions for audio and video submissions. I’m not sure on how to handle this. I set aside time for them and they don’t show or cancel sometimes. How do I get them to follow through. It’s only 20-25 min.

C cancelled coaching session, T volunteer clients can choose to follow through or not, F detached, A ?, R ?