If your instructions to us were for an offer advertised as "Buy one, get one free", we would have placed the order for that offer. We cannot be held responsible for the merchant failing to fulfill the offer.
There might be several explanations for why you didn't receive the "free" item for example, the offer expired, or there were limited quantities, or perhaps the "free" item is shipped separately and arrives at a later time. Any time you dont receive the exact goods you instructed us to order on your behalf, you need to contact the seller directly.