I don't think you will get the increase because it was obviously an honest mistake on the part of the company. Besides if they do "honor" their mistake and increase you, legally they can hit you the very next month with a CLD (credit limit decrease) and as I have learned this past month they can use any excuse they want when doing that because it is their card, you are just borrowing it.
I wish you luck though. It would be nice to receive a limit like that. I have a card, "A" as in only one card with only a $300 limit. My balance has never gone over 60 bucks, I try to keep it in the 20 dollar range, but in all essence that card is useless except to rebuild. And I found out yesterday that after my 18 months of good behavior they will no longer turn it from secured to unsecured. As George Lopez says: FTP Orchard FTP.