Do you have his name ? I do hope you guys can form as one team and file a report. Then what you can do is seek help from MCMC and NCCC to at least get some information from carrier (mobile service provider) on conman. Chances are well its going to be bit hard as you don't have his phone number , IC number nor even his name.

Make a police report , then seek help from MCMC and NCCC to try to get them the carrier to release customers data (which they rarely do). I believe they do like you have said if the amount is big

Forgot about the links :-

http://www.nccc.org.my/

and

http://www.skmm.gov.my/