Virgin Active contract *****

I had a gym membership from June 2017 to June 2018 for myself and my 2 kids, which I paid in cash in advance for the year. Yesterday 15 January 2020 I get a phone call from Virgin active collections saying I owe them for June 2018 because I did not cancel the contract. They then asked to proceed to take the debit from my I account, I said certainly not send me banking details an what I owe. I then found my cancellation email and forwarded it. How is it lawful that a contract can be paid in advance and expire and then a client still owes, is this not *****?