Failed online booking yet amount has been debited

I was making a booking for a Mango return flight online and paying by debit card. I got a message from the web page saying that the tickets for that flight got sold out during the time that my payment was being processed. At this point I don't have a ticket and the money has been reserved for purchase from my card so those funds are unavailable for me to use to book a different flight. I called the call centre and was told that there wasn't any reference and they wouldn't do anything about reversing the transaction until Mango has 'done their banking' and the transaction shows up in their account. They could not give me a time period in which this would happen. I have also emailed Mango and not recieved any response