> They screwed up the promotion, to the tune of hundreds of thousands of dollars
It's really hard to say from the given context that this was definitely engineering's fault.
You'll note that the various plans for resolving the issue involve updating the Terms & Conditions of the offer. That makes me think that accurate code was implemented against incorrect Terms and Conditions, rather than incorrect code was implemented against accurate Terms and Conditions.
They screwed up the promotion, to the tune of hundreds of thousands of dollars, and 3-5s latency for ads? :P
That is the only part of this complaint I find interesting.