Misleading Promo

Bought a very expensive face cream only because the website said "buy one get one free". So I bought one, but didn't get one free. Contacted customer service and apparently, you should put two in your basket to get one free. THIS IS NOT MADE CLEAR ON YOUR WEBSITE! I already opened the product so I can't return but I am going this to the CPC - your software needs to apply the promotion, you cannot advertise something and put the burden on the customer to figure out how to get the promo app****. And no, i do not want a R100 'courtesey voucher) I want the free product - I bought one, I want one free as promised. Order number ***377