Fees being deducted but account has been cancelled

I have cancelled my contract with the gym. I have correspondence confirming my contract has been cancelled. As per correspondence received from the gym my last payment was due in March 2015. The gym deducted a payment from me in April in error and is now going to deduct a further payment in May. No-one is able to assist me with this problem. One can only deal with Katherine at the gym who does not have the ability nor the authority to resolve the issue. She passes the buck and blames head office and the billing company for the problem. The gym has a policy where they deduct 2 additional payments a year, one in June and one in December. They conveniently deducted a payment from me on 31 May and then deducted a second payment on 01 June. I have been trying to get this payment refunded but to no avail. Now I am going to have to fight to try and get these other two payments refunded. It is clear that these entries are not done in error but are deliberate and dishonest. I would appreciate being able to communicate with someone who is able to address the issue and resolve it.