Basiclly they are goo. But once you pay money to them

do not count on they can refund you; also please talk Mr. Jiang again to see if USCIS need supplemental docs, if they charge you extra fees! As far as I know they may charge you for supplemental docs. Anyway ask them $5000.00 include everything or it is a basic fee.

Usually they may give you a choice: for example: $5000 include everything or $4000 basic+ $400/each supplemental doc