If you've recently upgraded your Android or iPhone, don't ignore a new warning from the team at O2. The UK phone network says it's vital that gadget fans think about what they are doing with old devices and trade them in if they are no longer of any use. In fact, new research from Virgin Media O2 suggests that the average UK home might be missing out on over £200 by sticking old phones and laptops in a cupboard and forgetting they are there. The longer these gadgets sit gathering dust, the less