Still making debits after due notice given to Planet Fitness

Been a very long paying member for over 10 years. Handed in my written notice to cancel membership which was acknowledged and to stop debits as from March 2020 and Planet Fitness just continues to debt my account No responses now from them or phone calls to rectify. They now owe me R1990.00. l am not happy about the poor communication. What's to do now as they keep sending debits?