What should I do if the freebie promises from a live-stream e-commerce event didn't sync to the warehouse?

I've fallen into this trap before while selling beauty sets in a live stream: the host added a 'buy two, get a sample' promotion on the fly, but the order notes didn't make it into the WMS. The warehouse shipped the original sets, and customer service was flooded with inquiries the next day. If I had only addressed the surface-level symptoms at the time, it might have seemed fine in the short…