최송합니다 pretty much never means excuse me in the way you are talking about. It is a formal apology. 저기요 is used when you want to interrupt or get someone's attention. 잠시만요 is a more common way of excuse me when trying to get through a crowd. 최송합니다 is if you are really apologizing. 최송 literally means to have shame or to feel sorry (in a more literal non colloquial sense).