BlueHenFlyer - you have my full sympathy on this. You obviously complained at the time and the problem seems to be that the FA gave you a false expectation when she encouraged you to write in to complain - if s/he had been more honest with you by confiding that your letter was only likely to generate a glib apology, perhaps you could have been more insistent and resisted this attempt to mollify you and have you accept a long trip in an uncomfortable and potentially dangerous seat.

I don't see why you shouldn't feel entitled to a discount, this is usual when we have to accept a sub-standard version of anything else in life.

In future, if anyone ever tries to put you in a seat that you have reason to be concerned about as a possible hazard if turbulance sets in - REFUSE!