Refund still not recieved

I lodged a claim for refund on 18 October 2017, due to Mango on strike and my flight was extremely delayed. Till this date nothing has been received. I followed up on 02 November, as I have not received any payment as yet, they advised that they are awaiting documents from me. Initially they did not advise me to send through any documents, fair enough I sent it through and received an email from Petronella Kgwedi on 09 November 2017 that the documents are well received and refund takes 7 - 14 working days. I waited until today and still nothing has been received. I contacted them again and they advised that they are awaiting documents from myself. That is when i have gotten furious and advised them the docs have been sent. I was put on hold and then only to be told that they are sending an email to the finance department to send through proof of payment as the payment went through on 30 November 2017. I triple checked my account and did cannot see any payment from Mango. I have sent through an official letter from my bank reflecting my account details as well. Utterly disappointed with the service.