Best practices cancellation from client

Hi. I have a group program where people can pay in 3 installments and from time to time some of them decide to cancel and stop paying (they do wire transfer not credit card payment which is more the standard in Switzerland).

Contractually, it is my right to ask for the full payment as they can access my whole content from day one. It takes time and energy but it is feasible. I am not sure it is the best way to show up for my business and reputation doing that.

I also don’t want to waste my time and energy on such things. Do you have any best practices in case of cancellation of a group program?