Change Flight - 4.8k in exchance for 1.2 - frequent guest.

Hi, I booked 3 flights from Durban to Jhb for my wife and kids, plans have changed and now i wanted to swop the 3 flights to 1 flight from Jhb to Durban,

Mango says the system cannot do this, I want to know if the individuals behind the system can accomodate me. i am returning 4,800 in return for a 1,200 flight?

surely this can be accomdated.