Dear support staff member or memberette,
first, thank you for taking the time and effort to help me.

Part One: Prologue
Not an hour have passed since I erroneously disbursed myself of 2.49 Dollars of the United Stated. Indeed I gaily parted with spare coinage seeking expansion of my Dishonored video gaming experience by means of downloadable content. Things looked bright until inspection of the 'coming soon' section of your fine establishment.

Part Two: Dismay and heartache
It soon unfolded that the particular edifice sought was not the item bought. Despondence overwhelmed me. I pained beyond what might be conveyed using words; reverting from the overwhelmed stupor (presumably to be whelmed as I must have been before) a fresh grokked truth blazed through my soul: in my eagerness I overlooked the title of the DLC I bought!
I was anticipating the release of the DLC "The Knife of Dunwall" and was enraptured so to see a DLC for Dishonored sold at the low low price mentioned. I stress that it was my genuine impression "The Knife of Dunwall" was indeed the thing for which I paid, my friend. Hubris sired downfall as surely for this humble shopperas it fells great men and kings.

Part Three: Unforeseen Consequences
I wished not to partake in "Dishonored: Dunwall City Trials" and am frustrated, foiled by my own eager oversight. I robbed myself of funds well needed to buy "The Knife of Dunwall" upon release. "The Knife of Dunwall" is of course the only of these two I wanted, yet life's cruel irony makes it the very item rendered out of my monetary reach. How happy was I such a short while ago, believing it be that which I procured. Woe! I was as innocent as I was dumb.

Part Four: A New Hope
Would you kindly refund my erroneous transaction?
Thanks in advance for thine comradeship (for you shared my burden reading this), and heartfelt salutations alongside honest admiration should you prove apt and worthy. I beseech thy, undo my folly. A man of such mercy is no mere hero. In fact, language and lore dictate that you, my friend, you, the doer of charity this virtuous and good and worthy of all merit, you and those of your immense stature must be regarded as Gods among men!