How to write an apology note

"Due to an act of blinding incompetence on our part, you received two Fivers on Friday afternoon, the first of which bore a remarkable similarity to Thursday's Fiver. We would like to apologise unreservedly for this foolishness and for any distress or embarrassment caused. We'd also like to promise it won't happen again, but it probably will, so we won't." Courtesy, the Fiver, The Guardian's tea-time take on all things football.