Don't want to payback

Buy a Pattern USB Mini Noctilucent Air Humidifier through Bid or Buy on 30 Aug. 2015. Pay R276. Use it for one night, and when I want to open it the next morning the magnets cling to each other and the one magnet was broken. On the 7th September I let them know it is broken and how should I go to return it. They put an SNC next to my name with the message \seller and buyer agree not to proceed with the sale". I did not agree to anything. Then they offer me another one but for R96.99 and I have to pay my own shipping of R79. I you calculate it "