Cadbury competition

<p> I went to Engen in springs thats located in ermelo road strubenvale, to redeem my martian in terms of the cadbury competition. The cashier had no understanding of the competition and insisted that i have to purchase my chocolates from their shop in order to get the martian, even though i showed her it says buy anywhere and collect at engen. We started an argument because she says im coming there with a WIFI code to collect my martian. They GIVE the chocolates to customers buying 4 in store and the gives them one martian, She does not know what to do with the code?? How must i collect one then if i MUST buy the chocs at that Engen shop?</p>