as I see, your in california. There has a been a case brought up about this and is currently in the legal process as we speak.
if your interrested this is documented on the wellsfargo website inside the "statements and documents" page, far right under "important documents"
a choice quote from the description of the charges: "Plaintiffs also allege that Wells Fargo, when posting debit-card transactions on a day, re-sequences those transactions from highest to lowest and thereby increases the number of overdraft transactions. Plaintiffs allege that these practices violate California consumer protection and unfair business practices laws and constitute fraud, negligent misrepresentation, and conversion. The lawsuit seeks monetary and injunctive relief from Defendant."
believe me, i've had over $1200 in overdraft fees since 2004 because if this exact thing. look at your statements and that is exactly what they are doing, re-orgranizing the charges from most to least so they get the highest number of overdraft fees possible.