Failure to deliver

I received the MAC promotional special via e mail, which included one free brush when you purchase a base and another MAC product of my choice. I currently didn’t need these products as still had sufficient supply left , however the special was so good as the brushes are wonderful and so expensive, that I decided to purchase my makeup products in advance to be able to get the free brush. Once the two products were in my cart and I was ready to pay, it allowed me to select my desired brush and I made the payment. My order arrived this last week and there was no brush. When I called and emailed to say it was forgotten. they rep**** saying.., oh the system is not great at keeping track of the sales and they don’t have any more brushes- all sold out. Surely before that order was dispatched I should have been notified that the product was no longer on offer and given the option to cancel the order? This is now the second time MAC have done this to me and it’s totally unacceptable. I cannot trust them for future purchases as they don’t deliver what they say.