回複:緊急求助, 發報價單的問題, 快要崩潰了
I don't think your client would stop talking to you for $400. you probably are thinking too much.  what you did was really not a big deal.  explain to your boss, then to your client citing miscommunication.
To your boss, jusr explaon what you were thinking.  there was no real damage.  everything should be fine. 
