I purchased a charger from ebay, it melted within a week and the trader wont help me, what can i do?

I bought a replacement laptop charger for my acer aspire on ebay from Elec-touch, this proceeded to break, I contacted them and they then replaced the charger, within a week the charger I had received as a replacement had melted and had caused fire damage, I contacted the trader and they said they would refund my money whilst also paying for the fire damage, but now they will not return my emails and they have not paid me the money, what can I do?