Cancelled membership but still debits

I cancelled my contract with Virgin Active at the end of 2020 and everything was fine till Virgin Active started debiting my account again in July/August 2021. I called their call centre to find out what was happening and I was told that when I cancelled my membership the consultant did not cancel my minor’s membership and they promised to fix that. To cut the long story short, Virgin Active is still to this day debiting my account every 15th of the month and I’m tired of just following this up. Can the Head Office assist me with this and return my funds please?! I honestly don’t know why someone thought it’s okay for a child to have a membership when the main member has cancelled their membership? And what is soo difficult with just fixing the mistake and just cancel this contract?