What do you mean by slapped? They had their QS lowered to 1? Or they just stopped getting impressions?
I have recovered from the former (which is what I call a slap), but only heard one case of someone recovering from the latter (which I call a ban). When we got slapped I talked to the Google rep, and they told us what we needed to fix. Once that was done they (much to my surprise) restored the account to normal. What fixed it for us was changes on the backend (specifically, where the lead information was processed after they filled out the form), so maybe the landing page look the same but something in the background got changed?