FINNAIRs so called Campaign
 

I recently bought 2 adult and 2 child tickets during a Finnair "Campaign". I presumed this would be at a special price. I paid 29960 RMB (around $4000) for these "Campaign" tickets. When the "Campaign" period ended I checked the price and found that the same tickets for the same flights at the Regular Economy Saver rate would cost just over 25000RMB (around $700 cheaper).
I contacted Finnair saying that I had been misled by the phrase "Campaign", maybe unintentionally, and asked them to reimburse me the difference or give me a voucher for the amount for my next flight. I have been spending $4000 twice a year for the past 4 years with them.
They just said that the "Campaign" tickets were non-refundable, non-exchangeable and they could do nothing.
Is this not illegal advertising? Or is an airline free to mislead people to buy tickets in the belief that they are getting a special price when in fact this "Campaign" price is considerably more expensive than a regular price that can be released as soon as this sales period is over?

I think you answered your own question when you stated you "presumed" that it would be cheaper. You know what would save folks a lot of grief and anger, is to not look back once you purchase your ticket. Seriously, I mean what would happen if Finnair gave you the difference of the ticket and it goes even lower? Should they keep refunding? When does it end? I think you should ask for the difference in a voucher, but it is my belief that once you buy your ticket, you really shouldn't re-check the fare, just go on to the next step.

+1. Fares change all the time. A few months ago I was shopping for fares in late November to fly over the Thanksgiving holiday weekend. After a few days of checking I saw what I felt was a good deal and bought the ticket. Just for fun, since I had been tracking this fare manually for several days, I plugged in my itinerary details to Yapta.com to see if their website could do a better job of fare tracking than I did myself. In the first few weeks and months I was gratified to see that the fare fluctuated upwards and at one point was almost double what I paid! I was feeling really good about my purchase but then recently the fare shot down and at one point was actually almost $50 dollars less than what I paid. Oh well.

I know it's not nearly the $700 difference you're posting about but for my ticket $50 represents almost a 20% savings. I look at it this way. When the fare for the exact same itinerary was nearly double what I paid United wasn't calling asking me to pay the difference. I could have requested a voucher for the $50 difference when it was in my favor but that would have cost me $150 as a reissue fee. Not a good trade off. My point is that when you first purchased your tickets you thought they were a good deal otherwise you wouldn't have purchased them at that price. Don't sweat what happened to the fare afterward. Next time you'll know to carefully research the fare your about to buy and perhaps wait for a better deal.

In relation to your substantive point, the word "campaign" is meaningless in terms of consumer law. Had Finnair used terminology such as "Sale" or "Discount", these do have specific meanings, and you might be able to try and get some remedy, but this would depend which market you bought the tickets in. In the UK for example, the OFT (Office of Fair Trading) has taken enforcement action against Ryanair for misleading advertising, as has the UK Advertising Standards Authority.

I think this is a case of caveat emptor, but the dynamic pricing used by airlines is so opaque, I think the only real remedy is to not fly with them again.