ASIM stands for "Assistant SIM Master". They are people who do not have characters, and who have access to a lot of backend information and tools concerning the Combine. They are responsible for, among other things, investigating and enforcing rules and dealing with support tickets.
As for "often", it totally depends on your definition. There are several active ASIMs who will, when they have time, conduct the investigation and deal with the handle request.
Couple days usually, sometimes more. Patience is a virtue.