SB - Cancellation Fee Feature in Subscription Model

We are looking for a way to add a cancellation fee for subscriptions in our service. Currently, there is an option to set a cancellation policy based on the number of successful payments (e.g., allowing cancellation after 4 payments), but we would like to implement a feature where a cancellation fee can be charged when a customer cancels their subscription after the grace period. This would help ensure that the subscription model aligns with our business needs and adds an additional layer of commitment for customers.