No refund at VIRGIN ACTIVE

I cancelled my gym membership and Virgin Active STILL deducted my membership fee at the end of the month. I made an enquiry and they said because I cancelled on the 5th (before the 15th) they will refund my money, and they apologized. It's been another month and VIRGIN ACTIVE STILL DID NOT REFUND MY MONEY. My favourite gym, but they can't be trusted