Wow... recently, I had an issue with them, and LITERALLY got the EXACT same e-mail.
I was on an early afternoon flight home that was canceled and we were automatically switched to a flight 6 hours later. Unfortunately I had a conference & dinner benefit to attend that night that I had paid $170 for that, because of the delay, I fully missed. I got that e-mail and responded, telling them their blatant hypocrisy was pathetic, and that, yes... I could somehow understand them not calling, e-mailing... but if they really wanted to pull this, they could at least have the lady who checks you in tell you. I had to discover it after checking my bags and looking to see my departure gate. Sad... the actual check-in rep couldn't even say anything! I told them I would accept full compensation for what I had missed or a roundtrip voucher, straight up. There was another woman on my plane who had missed a connecting flight to AUSTRALIA on the ticket that she had booked months in advance, as well! It wasn't just me, it was almost all of my plane.
That was followed with an "I'm sorry, there's nothing we can do, " and I told them to check again, because I more suspected there was nothing they WOULD do.
Then I got offered a $15 coupon off my next airfare - oh, that made me almost pee laughing. Once again, I told them that was horribly inadequate and kind of a joke, they told me it was all they could do, and I told them to review it AGAIN.
Next, they offered my an e-voucher thing (i.e. $15 off of $199, $25 off of $500, yadda). Well, I travel to to see my boyfriend, a $220 ticket, every other weekend. That has even less value than the first offer! Once again, I said that wasn't going to work, and repeated my initial request. The service agent e-mailed me that, unfortunately, there was nothing more s/he could do, and (by this point, getting pissed), I replied that, unfortunately that was not my problem (as they had earlier told me about my issue!) and that perhaps s/he could find someone capable of doing something beyond cutting and pasting replies to me. I also informed them that small claims court was very inexpensive for me, worth my time apparently, because it would cost less of my time than actually trying to deal with customer service, that they would escalate my claim to a lawsuit (as they have almost 100% of the time), that lawyers were sure expensive, but it was OK, because I wouldn't have to retain one like they would.
Funny, someone who actually even spoke clear English called me the next morning to inform me that, in addition to the first two items they tried to pacify me with, one for $15 and one pretty much useless to me, they had issued a $200 gift certificate to me and a Region 1 aircheck (good for continental US roundtrip airfare) and hoped that, combined with the other two, we could 'reach a satisfactory resolution together.' Most amusing yet, they didn't even want proof that I had actually had been scheduled for and paid for my conference and dinner benefit. Idiots. Though in my case, I was not lying, that stupidity just shows how lacking they are in intelligence. You'd figure if they waste that much time wasting our time with those e-mails, they would have enough time to verify my story and insure that I actually DID deserve compensation. One fax. Sad...
In sum, if you write them about a dozen times, and every time they tell you they are unable to assist you, just write REALLY long e-mails back (most of mine were about a page long). Also, randomly in the verbose e-mail, drop in stupid but personalized questions. That way they actually have to read it. I actually cut and pasted parts of my original e-mail in subsequent ones (much as they do), to make the burden of looong e-mails less taxing. Then, every time they apologize and tell you there is nothing more they can do, tell them it's not good enough in about 900 words. It's amazing how much, though "there is nothing they can do, " that they come up with after a few e-mails.
If none of that works, always remind them that, if pertinent, you are a very frequent traveler (as I am), and that you know your rights - to sue in small claims court, which generally costs under 20 bucks, and that it's going to cost them a hell of a lot more than it's worth in comparison to just basically paying you off in the form of a crappy, limited travel-date voucher.
That small claims court bit actually works very well in my experience. I've used it on Sprint, the worst company in the known universe, after 7 months of paying for and not having a phone their repair center lost and extending my contract a year without any consent or request from me. Once again, with them, I had an English-speaking guy call me THAT day (Miraculous, considering it takes an hour to get a rep who is ALWAYS from India, as are all the people he could ever transfer you to. None of them can spell Jessica, even when I spell it for them. Then it takes an hour + of talking to them, and being transferred incessantly, to eventually get a case number that will have never existed next time you call!)
And, no, I have never sued anyone. I think our society is too litigious; people should stop suing each other. It's sad that you have to threaten suit to get ANYTHING at all done. Better than nothing, at least.