Be it further enacted, That the director of finance shall collect the merchants ad valorem tax at the same time and by a similar procedure prescribed by general law for such taxes due the state and county, with such modifications as may be made by ordinance, and such taxes due the city shall be subject to the same penalties and interest and all other provisions for the enforcement of county and state merchants ad valorem taxes. The council may request the county officer collecting state and county merchants ad valorem taxes to collect such taxes for city and to remit the proceeds to the director of finance, in which case the said county officer by agreement may collect and remit such city taxes, for which the city may pay him a reasonable fee for rendering such service.