The registration in adult group lessons is based on a self assessment, please check the NTRP guide below:
https://www.tenniscanada.com/wp-content/uploads/2015/12/Self-Rating-Guide-English.pdf

If your tennis skills don't match with the level you registered for, you will be suggested to join the appropriate program if a spot is available or to get a refund for the remaining classes.

Cancellation policy:

Registrations in our programs are final sale.
We don't offer a refund, credit or make-up classes for missed classes.
No subs are allowed.