salam
i also got the rejection letter for absence of multiple documents
i had no guidelines but
what i did
i again copied all my documents and gets attested them from a friend and acquired a fee challan from Urdu bazar karachi nazimabad, filled the challan in any national bank branch and send all documents to spsc head office address
then i called there and the guy told me that we have received your documents and we will send your admission letter on this coming monday

do the same if any body has rejection letter for absence of douments

i hope it helps.