willt

hi there can anyone help me here? Well heres what happen i made a trade on this guy named robdabest10 and he accept the offer and send me a invoice and it says sold to me and the status say complete already. the trade is my airsoft for his rtr revo. now all of a sudden when i send my item and gave him the tracking number he change the status to incomplete and hes selling the same item what should i do

heres his link that he change earlier
http://www.rcuniverse.com/market/item.cfm?itemId=232212