Planetspark — Not refunding

I have enrolled my son in planetspark in December 2021 and paid for 80 sessions. After attending Couple of classes my son lost interest as his teacher was not slowing up on time and it was same even after changing the teacher. So I have stopped the classes after about 20 sessions and requested for refund but they are not at all responding. I strongly discourage to join their kids in planetspark.