My guess (probably nothing new to people here) is that the letter is also an automatic reply. Probably a person has read your initial letter, has filled some fields in a form with the date and place, clicked OK or similar, and that was it... Have you ever tried to write, in your compliment letter, something like "please do not use [standard reply formula#1]" and see what happens?
Well, the easy thing to verify that theory is to post a praise to some random lounge agent and see if the answer is worded the same.