Any bidder who seeks to withdraw or modify a bid because of inadvertent computational error shall notify the purchasing agent no later than three working days following the bid closing. The bidder shall provide worksheets and such other information as may be appropriate or required by the city purchasing agent to substantiate the claim of inadvertent error. Failure to do so may bar such relief and allow recourse from the bid surety, in the discretion of the purchasing agent. The burden is upon the bidder to prove such error. [Ord. 06-18-2013A § 2].