After playing its first two games of the season away from home, Napoli is scheduled to play Sampdoria at San Paolo on Sunday (AEST) before the visit of Liverpool in the UEFA Champions League three days later.
But according to Ancelotti the work has fallen short of what was promised, and suggested the council of the municipality of Naples, which owns the ground, showed a lack of regard for his team.
In a statement published on the club's official website, Ancelotti said: "I saw the conditions of the San Paolo dressing rooms. There are no words.
"I accepted the club's request to play the first two games away from home to allow the work to be completed, as was promised. In two months you can build a house - they have not been able to redo the changing rooms!
"Where should we change to play against Sampdoria and Liverpool?"
The planned redevelopment works included big screen displays, upgraded lights and a new surveillance system, as well as new changing rooms.
The council reportedly said the failure to complete the works entirely would not affect Ancelotti's team, but the Napoli coach disagreed vehemently.
"I am outraged by the incorrectness and inadequacy of those who had to carry out these jobs," he said.
"How have the region, municipality and commissioners been able to disregard the commitments made?
"I see a contempt and a non-attachment to the city team. I am dismayed."