Greedy Gym Group

I had a gym membership at Muscle and Fitness which I paid via monthly debit order, which I cancelled in January, I signed a cancellation form at the gym and signed up for a new gym membership contract which I paid for upfront in full. I was assured that the debit order would be cancelled timeously and that no further money would be deducted from my bank account via the debit order of the cancelled gym contract. I have now had money deducted from my bank account for the monthly payment of the gym contract I have cancelled, via the debit order I have cancelled. I am now effectively paying for two gym contracts, one of which I have paid upfront for a full year. This is theft and a violation of consumer rights, it is totally unacceptable.