can anyone just put in a false address ??????????

a lad i know was sending me messages through ebay
but i didnt know untill someone else told me that he was
taking the piss and asking what my reserve was, i told
him £1300, the last bid before the end of auction was about
£600 but then someone just put a bid in for £1500

thay have been a member since 8/03/05 and have no
feedback is this the same lad do you think under a false
address, the lad i know is from newtown powys but the
buyers address is in newport near telford but i think its
a false phone number with it aswell.

what can be done if thay dont respond to my email's ??