A. After the establishment of a district, the council may, after complying with the notice and hearing requirements of Section 13.34.030, increase the amount of charges applicable to properties within the district, based upon the original apportionment formula, if they find that due to factors of inflation the actual or estimated total installation cost of the public facility has increased by more than twenty percent.

B. Where the amount of charges within the district is increased pursuant to subsection A of this section, no such increase shall be applied to any parcel or parcels or portions thereof where such charges have been paid by or on behalf of the owner or owners thereof at or before the time of adoption of the notice of intention by the city council. Any parcels developed after the adoption of the notice of intention shall be charged at the increased rate subsequently adopted. Nothing shall prevent an owner of real property within the district from paying charges prior to development in order to prevent future increases in charges.