Zero communication, it's frustrating!!!!!!!

Regret ever signing up with this academy. For a longest time, I was so unhappy with their service and decided to just deregister my son because their level of unprofessionalism is unmatched. I then paid my account fully and even paid their deregistration fee. Since last year early November, I'm trying to get hold of them with no luck, they ignore all my communication both via email and WhatsApp. What's shocking is they keep sending emails for invoices and texts on WhatsApp about handing over my "owing account" because it's long overdue. What the f***????