Skymilesdining

So I'm in Delta's mileage program and in August saw on the Skymiles Dining page that if I signed up by a certain date, which was 4 days into the future, I would get a bonus of 3000 extra miles upon my 1st purchase within 30 days, vs the usual 1000 miles. So I signed up about 10 min after I saw that. I used my skymiles dining linked card to buy dinners exceeding their minimum charge right away. BUT I only got credited 1000 bonus miles instead of 3000. I call the 'customer service' line and talk to a low level rep, explaining my situation and asking for a mileage adjustment pursuant to what they advertised. He said no it expired the previous month (NO IT DIDN'T - I saw the due date very clearly. I only look stupid), then I asked him to take it up thru his supervisor, which I suspect was just a first line sup with no authority, and she flatly refused in about 10 seconds. Now as an IT veteran, I know it's possible to archive the pages whenever they modify it, but these guys probably aren't saavy enough to do that, so I can't prove it. Maybe I should've taken a phone pic of it, but I didn't expect these guys to be noncompliant with what they advertised on their page. Advice ---DON'T BOTHER JOINING THESE GUYS. THERE IS NO GUARANTEE THAT THEY'RE GOING TO GO BACK ON A REWARD/BONUS THAT YOU MAY BE LEGITIMATELY ENTITLED TO! I'm pulling out of this program - I have absolutely no confidence that the administrators of Skymiles Dining have ANY SENSE OF CORPORATE/PERSONAL INTEGRITY!