Hi,
Unfortunately, without a proof-of-purchase they'll have little chance of getting any software support from Cisco.
If they have the original box then that should have their original PO number on it - and their accounts should be able to trace on that.
Finally, depending on what version they're running (probably old if they can't remember where it came from) they might not be able to get a SAS contract anyway. (Anything 3.2 or older is obsolete).
HTH - plz rate if useful
Andrew.