Akon - sorry, blame it on me.
The song is “Apologize” by OneRepublic, though it was recently remixed with/by some rapper. You’re the second person I’ve heard say they don’t hear the “a” (the other being my dad) but it doesn’t sound like the a is unvoiced to me. ::shrugs::
Ringside “Tired Of Being Sorry”
Howie Day “Sorry, so Sorry”
Splender “I Apologize”
The Sounds “Queen of Apology”
2 Girls Later “Apologies” (you download the song from their purevolume page)
Loss for Words- Tait
“Hard To Say I’m Sorry” by Chicago
You don’t want to come off as too apologetic, so to balance things out why not burn a copy of Louis Jordan’s Ain’t That Just Like A Woman:
You can buy a woman clothes,
And give her money on the side,
No matter what you do,
She ain’t never satisfied
Ain’t that just like a woman?
Ain’t that just like a woman?
Ain’t that just like a woman?
They’ll do it every time
Sweet Surrender by Sarah MacLachlan. Kind of an oblique approach, but probably does actually say what you want to say.
I’d only send that one if I was owed an apology. If it was mutual, I’d send “National Apology Day”, same artist. 
*** Ponder
I think it just called “The Mea Culpa Song,” but I’m getting no help from Google here.
As I recall, the first verse goes like this:
“I did it, I did it, I did it.
I did it – I’m guilty as sin.
I did it, I did it, I did it.
You’re right. I’m wrong. You win.
What ever it is, I admit it.
I’m a jerk, I’m a slob, I’m a boob.
I’m the lowest of low
So now that you know
Could you move there? You’re blocking the tube!”
It gets worse!