You can suggest a change in the listing -- not here, of course, that's all taken care of back at the website. The "update listing" link will create a request for an editor to re-review the site (with a view towards the necessity for the changes suggested, or for other changes.)
Such a request is usually reviewed fairly quickly. Naturally, if it LOOKS like spam, and the current listing has no obvious problem, the request might well be quickly written off as one of the 90% of suggestions that are spam.
So, to get the most favorable review:
(1) Avoid anything that resembles hype or keyword-stuffing. The ODP editing guidelines are pretty good at describing an appropriate title and description: as are (in an absolutely negative way) introductory marketing textbooks -- avoid anything, absolutely anything they tell you to do, and you'll be perfect.
(2) Make sure any change requested can be easily verified on the website itself. The website speaks for itself with absolute authority -- anything else is just hearsay. (We don't know and don't care whether the "update" suggestor is the webmaster: the whole ODP structure is designed around the principle of "don't do anything for your own site that you wouldn't do for a competitor.")
(3) Remember, the intent of the ODP listing is to be accurate and objective: mention ways in which the listing (or site placement) simply doesn't accurately the website as it is.
(4) Remember, editors' decisions are driven by the guidelines, not webmaster whim or edict. If there are no ODP-guidelines-compliant reasons for a change, it almost certainly won't happen.
(5) Editors don't work on timetables, schedules, or priorities imposed from outside. We don't know when your suggestion will be reviewed (so of course you can't know either) -- just that for the sake of directory accuracy, many active editors give priority to update suggestion.
(6) Remember, there are many things in the world that ODP editors simply will not accept responsibility for, such as nightmares. It's your job to seek such medical help as necessary -- see
http://dmoz.org/Health/Conditions_and_Diseases/Sleep_Disorders/ for advice.
(7) Worth repeating: all ODP incoming communications are filled with peremptory, accusatory, repetitive, blustering, hyped spam. Stand out from the main crowd -- be succinct, accurate, non-judgmental -- the sort of suggestion that seems like it might have come from the public-spirited netizens from which the ODP draws most of its energy. (And if it's too late for that approach and you've built the other kind of reputation -- write the ODP off as a lesson in burnt-bridge communications and go on. [Of course I don't know if the last applies to you -- just that it often does.])