From my perspective this is really a customer service issue as they did not say they canceled the promotion, but rather said we are not sure if they we will be able to honor the promotion, we are still deciding. This is the issue, by their own admission they advertised something that they are now considering not honoring and their communication with their customers is terrible. This is bad customer service.I think we'll have to agree to disagree.
The way I look at the advertising question goes like this: Say a Brick-and-Mortar shop makes up signs advertising a special and hangs them in the front window and around the store. Then, the promotion ends and they take all of the signs down and put them out in the alley with the trash. Then, someone goes searching around the alley and finds the signs and tells all of their friends about the signs. Then, everyone grabs a sign and walks in the door and demands the special. Are they owed the special? I say, "Get the f*&k outta my store with that."
Also per your analogy of a brick and mortar is not 100% correct, it is more like this " I advertise a big sale and I marked down a bunch of items for the sale. The sale ended, I take down my adds but I forget to change the price tags on the items. When a customer goes to check out what I ring up at the till is higher than the price tag on the item, do I honor the price tag or force the customer to pay higher prices because I am no longer advertising the sale?" Simply put, the store screwed up and is now presented with a customer service issue, the only question is how do the handle it.
I think we'll have to agree to disagree.