Struggle to get a repair to my parcel!

Hi<br> <br> I recently bought a laptop from bidorbuy and when I recieved the parcel the laptop worked for 1 day and then suddenly the usb ports stop working. I got a second opinion from a friend of mine and he said that there had been a power failure and it make a short in the laptop. I asked the seller if I can sent the laptop back she said yes but I have to pay for the shipping. Okay cost me around R250 . Now I got an email saying I have to pay R600 to sent the laptop to China for shipping and any additional charges I also have to pay!