Woolworths taking their customers for r a ride

On 6 November 2022, I ordered Lindt chocolates that were on promotion -buy any 3 pay for 2 festival. I only received 2 and was told that the other one was not in stock. I was told that my shopper tried to call me but they couldn’t get hold of me. I was told that there was nothing they could do for me. Today, 13 November, I placed the same order but chose a different chocolate, and the same thing happened- I didn’t get my third chocolate. So what I don’t understand is why does Woolworths run this promotion when they know that they no longer have these chocolates.