If it is a direct debit, you can claim it all back under the direct debit guarantee.
I had this on some dodgy mobile phone insurance company that did it to me over a period of 3 years.
Phone the company in question and ask for a refund under the direct debit guarantee. If the company refuse, phone your bank and get them to claim the money back under the guarantee. If the bank refuse, ask to speak to the fraud Dept of your bank and they will then see to it that all the repayments are made within a number of working days.