Bad customer services

On the 17/12/2015, I submitted all the required documents for cancellation of my mothers return airline ticket due to medical reasons and was advised that It will be processed and a voucher issued. 3 days passed and I did not receive any feedback, tried calling the refunds section but there was no answer for 2 days on multiple attempts as well as multiple emails sent with no replies whatsoever. I managed to get through on the 23/12/2015 and the agent advised that the ticket has been cancelled but she sees no notes about the voucher. She advised that I send her the email which I did as she would escalate. Another 2 days have passed and I am still awaiting feedback. This service is unacceptable. Does mango have a shortage of staff or they just practice bad service?