Hi I'm just looking for some advice,i won an apexi boost gauge off eBay,received it yesterday,opened it up and looked at it and thought the quality of this is poor and no fitting instructions,so went on Google and looking at pictures of genuine apexi gauges I believe I have bought a fake,have contacted the seller,still to hear back from him,if he says its genuine and hes not going to do anything about it,how do I stand?

Say its faulty, send it back and get a refund.

open a PayPal dispute

If you paid by PayPal you can dispute it. I think the item has to be "Not as described" which is a bit contentious, you would have to have some way of proving that it's definately not a genuine APEX'i gauge