The City shall give the Company a minimum 6-month notice prior to the request to implement any adjustment in the percentage of franchise fee to be collected pursuant to Section 114.10 hereof. The City agrees to modify the level of franchise fees imposed only once in any 24 -month period. When any such Ordinance increasing, decreasing, modifying or eliminating the franchise fee shall become effective, billings reflecting the change shall commence on an agreed upon date which is not less than ninety (90) days following written notice to the Company by certified mail. The Company shall not be required to implement such new percentage unless and until it determines that it has received appropriate official documentation of final action by the city council. In no event may the percentage of franchise fee exceed the statutory amount authorized by Iowa law.