Discord In The End Note

Something's wrong
In this song
'Cause it's ending on a low.
But the score-sheet
With the beat
Points to high.
I was sure--
You concur?
That the last note should be A.
But they played--
I'm dismayed--
A low F.

For so long
Heard the dong--
Notes I swear I used to know.
But this feat--
Incomplete--
Makes me sigh.
So I err,
I aver.
Things have not gone the right way.
And this grade
Now waylaid
Makes me deaf.