If the district shall file its objections, in the manner provided in Section 29726, to the annexation to a special service district of territory annexed to a city included in a special service district, the territory shall not be annexed to the special service district, except in the manner heretofore provided in this Article 6 (commencing with Section 29710). The district may withdraw such objections by filing with the city clerk a certified copy of a resolution of the board stating that such objections are withdrawn. Thereupon such territory shall be deemed incorporated into and annexed to the special service district, as provided in Section 29726.