I worked for IASCO for 8 years but they are only in Japan as far as I know. It was more a company than the present rash of agents. The best agent for me is GAP. I was with them for 5 years and they were always responsive and understanding. One fact that one must remember with Korean Air is that the company can change any item in the 'contract' and (all)the agents can't do a damned thing about it.
Don't expect too much, collect your salary, and you will not be disappointed.