Nestle Competition

I would like to understand the logic of the Nestle competition. Bought myself an Aero Peppermint. Win your share of R3.5 million in cash and prizes....but please explain... the same barcode is sent to *120*440*last4digitsofbarcode#. All this at 20c per sms. How do you then select the winners with no unique code?? It is in fact the same barcode. Some transparency would be appreciated.