Keeping debiting me after my contract has been cancelled -

I took out a contract with Planet Fitness Just Gym Glenanda on 1 February 2017. In informed them on 31 January 2019 on my intention via a signed letter to not renew my contract. I did go into the gym on the day but was told by a consultant that they coudn't process it and needed to call the customer support. She called but was not attended to after 15 minutes so emailed my letter to the email address she had provided me. They acknowledged my email and provided me with a reference number. At the end of February I noticed another debit order had gone off. As I am not in country at the moment one of my family members had to follow up. They have just informed us that they will take another debit order this month. Please can someone assist me with both ensuring this is cancelled and I am refunded for the past month's ******* debit order. I enjoyed my time at this gym but this just leaves a sour taste in the mouth when you were a client for two year's and are treated like this