Refund still not granted

I paid back my wonga loan manually and the debit still went through, which means a double payment was made. I contacted Wonga on the 3rd of February for a refund and they said 24-48 hours, I called again last week in the 11th and they said the same. It is the 17th and yet there is still no refund. This is unacceptable. How come when we take the loan, the money is sent instantly but now its been more than 2 weeks. I'm disappointed