I dont know of any tricks to make them go faster, but, I disputed online, and Experian deleted in about 12 days and TransUnion deleted in less than 20 (i'm not sure how long it took because i did not get a confirmation; i just pulled my report and saw the account was not there). I'm still waiting on Equifax.
In some ways you should WISH they take their times. Because if they take longer than the 30 days, they have to remove (or correct) the account.
Maybe you should also send letters to creditors telling them to delete the items.