Claimed errors in the calculation of assessments shall be brought to the attention of the finance director, who shall determine whether there has been an error in fact. If the finance director finds that there has been an error in fact, the finance director shall recommend to the council an amendment to the assessment ordinance to correct the error. On enactment of an amendment, the finance director shall cause the necessary correction to be made in the City lien docket and shall cause a corrected notice of assessment to be sent by registered or certified mail.