The situation is pretty much sorted now, try to stop blaming others for what happened, and just be grateful that she was even added to the show..
Song: http://www.youtube.com/watch?v=gIuotFZnBtk

Derpy is partually a creation thanks to the community, Originally being an animation error, she got noticed by the fandom and thus the name derpy was born.
Derpy was eventually adapted in a episode.
Sadly complaints have been brought up on itunes, Derpy will change into a background pony and will not be on any itunes episodes anymore.

Do not message Hasbro or studio B, studio B needs our biggest apreciation for even making derpy reality and hasbro was kind of forced by itunes.