Similar situation for me. Amex have confirmed to me that I passed 20k in Dec 09 but they can not force Hilton to give me gold status and when I inquired to Hilton this was their response -

Dear Mr. S,

Thank you for your message to Hilton Reservations and Customer Care. It is my pleasure to assist you today with your account.

We will update your HHonors account to Gold VIP tier status as soon as American Express sends the authorization form to our office to be processed.

So it seems like I will have to wait until Amex's 'system' gets its act together.