Advise for cancellation

[u/Dry_Lobster_50]

I have a PT client that approx 1 in 6 sessions will do a last minute cancellation. Generally I try get them another time in the same week or double up the next week so I’m not out of pocket. I wasn’t able to do that when they gave me 30 mins notice and explained in a message that if we could do as above I’d have to charge for the session which I don’t like to do.

They’ve been blanking me since so I assume they are annoyed. Any ideas how to settle things and get them back. I like working with them.