Continues to debit accounts after cancellation

I called Planet Fitness to freeze my account as I was 8 months pregnant and was not going to utilize the gym for the next 6 months. They confirmed it was frozen but continued to debit my account, after giving birth 2 months later I called them and they said they need a letter from the doctor to confirm I was pregnant and I said I already gave birth. Then I decided to cancel as they confirmed it will be frozen but 3 months later came up with that story of a letter from the doctor. They then cancelled my membership and sent an email confirming this but continued to deduct another 3 months afterwards. Upon numerous calls they keep saying they will investigate as they will retrieve the call of cancellation and will come back to me, they never do. The agents do not reply to my emails and continue to deduct from my account. They cannot retrieve the recorded calls as they see a opportunity to fill their pockets for the last time once the clients wants to cancel. This is so ********* as I have given them the benefit of a months prior notice and 3 months down the line the still deducting. Becareful when joining them...