bad name seller

he traded me 15m for an acc. we got the cash bye going thru rs4s.com
they said in 3 days the 15m would be on my acc.3 days later i pmed bad asking him if they had it on there and he said yes give me the acc info and ill give u ur accs pw. so i gave him all the info and he never sent a pm back. well the next day he pmed me and sai soz my internet was down (it showed he had ben on 3 times later thaT night on the last activity.well the next day he pmed me a pw and i tried it and it didnt work. he had already got off.it has ben the third day aqnd he has got on everyday and ive sent 6 pms total asking for pw but he keeps ignoring them...
can some1 help me plz?