I did not express disagreement with the fare or request a refund; I simply asked to be charged the initially quoted amount
This seems to me to be a very thin reed, and I cannot help but wonder if the tone and length of your initial email to LH was similar to that here, and perhaps reasonably confused the agent as to what it was that you wanted.
As always, a post or complaint is most helpful when shorter and simplified. (I.e., drop stuff like you were stranded in a country where you didn't speak the language, unnecessary rhetorical flourishes and other details)