so what you are saying is that you sent the bitcoins to an address that you pasted your order number into. In that case they are likely irretrievable.
Not at all. You can't send Bitcoins to an address in format xxxxx-xxxx-xxxx-xxxx-xxxxxxxxx - it would error out. "-" is not a valid address character, and there's a checksum built in to Bitcoin addresses as well, to make sure you don't accidentally send them to the wrong place.
That said, BitInstant is bad at support from what I've heard. Keep bothering them, hopefully they'll get back to you and figure out what happened.