No communication between refunds and financial dep

I have made a double payment to mango airlines 21 May 2015 which they have confirmed. Since then I have phoned and sent e-mails again and again. I sent all the required documents with an official bank statement showing the payments and my banking details. The only response I get is that my bank account number is invalid. Speaking to any of the friendly staff at refunds lead to nothing. They always check and say the request was submitted. Scelo actually once said he was sorry but they have a backlog on payments and the problem lies with them and my payment is in the next batch. Sadly I am still waiting and their response is again that they will find out. Their manager Mr Veldsman is never in the office and they are not allowed to give me a contact number for the financial department. They cannot solve the problem and I do not understand what the problem is. Is there anyone out there who can solve this problem.