There're alot of remittance service counters/companies. They
operate by license from MAS (monetary authority of Singapore).
The purpose is for workers to send money home to their
country/family. Its nothing illegal, as long they have license from
MAS. Its to send money home...why else do you think the foreign
workers come here for?
If you have reason to suspect they are doing anything illegal/no
license, call MAS and give them the information. If its true, MAS
will then ask the police to take action on behalf of them. The
police doesn't go around checking such - its not their duty.
How old are you, by the way? Remittance sercices are perfectly
normal and legal.