Inferior Quality of Goods

I purchased a Powerbank from them on 26 February, and when I got home I tried to use it.<br> The thing is absolutely useless, it does not charge, keeps on switching off.<br> Tried to take it back but they refuse to replace it as it has been \used". How can you use something that doesn't work?<br> Will never purchase from them again. Cheap Chinese Imports of inferior quality. """