As per iStore Vodacom requires a Bioemetric check - why????

I would like to know from Vodacom why upgrading a phone contract in iStore and upgrading in Vodacom have different requirements. I recently tried to upgrade my contract at iStore but my biometrics were not registered and was told by iStore that Vodacom have instructed them that without this they not allowed to release the phone. Yet I went to a Vodacom shop last week and upgraded my contract and got a new phone just using my ID book.