Noted, so we can safely cross the possibility of them rejecting the documents being submitted simply due to the document clashed with their preexisting database, namely you already used it to verify your own account to level-4 KYC? Or perhaps someone else on the house already use the same document [by same, I didn't mean the exact same, just the similar documents with different date of issuance, but still the same ownership, nonetheless] for their KYC?
They simply don't want to verify the account and withdraw the money, it was crazy to try anything else.
Well, if the same [but different, same in the sense of the document from other date of issuance] documents already in their system because someone else in the house already use it to verify their data, maybe you or your cousin's own family, it'll explain the constant rejection, as the data clashed.