As Ubasses has indicated, the method of payment is important. If you paid by direct debit then you're covered by the guarantee:
http://www.thesmartwa...ctDebitGuarantee.aspx
Contact your bank and insist upon swift repayment of the money into your account.
However if you provided the company with a 'continuous payment authority', by giving them your debit card details they might be within their rights to take the money. Even if they're not, the bank was legally obliged to give them the money and has no obligation to refund you. (You can only get your money back by suing the company, which would take ages and clearly isn't going to help you).
http://www.financial-...utomatic-payments.htm
Contact your bank, in the first instance, to see if they can help you. Then contact your mortgage lender (and anyone else who will be expecting regular payments from you) to explain the situation. Then (unless your bank can quickly assist you) you'll have to look into getting some form of loan or selling something to get a few quid in your pocket.
Chris