No Refund

I booked a flight in August 2017 for my son to Jhb to catch his connecting Flight to Dubai. I received a message the flight was re scheduled and was asked to confirm if this would be ok but the time difference he would miss his Jhb to Dubai flight. I was then informed i can contact the refunds department for my refund. It is now January 2018 and i have only received a portion of my refund. I have been phoning for over 4 months and get the same reply, they will have to check with the Finance Department, not only is this what i get told but everybody i have spoken too does not know why i have not been paid as it has been sent through for payment. I have e-mailed no reply, phoned but no call back as everytime i phone they will contact me. WOW all this and i have got absolutely nowhere and no idea what to do next.???