Sidewalk hazard/violation. And MTA subway station is in front of my building.

Situation:
I have a building on a busy street with a busy subway entrance. The sidewalk in front is 30 feet deep (15 feet my property plus 15 feet MTA property).
I received a violation from NYC department of transportation. (broken flags, tripping hazards, water ponding). The violation lists items on both my property and MTA property.
To clarify the water ponding issue:
Water ponds on the seam where my sidewalk meets MTA sidewalk. A properly pitched sidewalk is pitched so rainwater will flow from the building down to the street.

Problems:
I have recached out to the MTA regarding this. But they have not responded.
If I replace my flags and the MTA does nothing, the ponding will remain the same or get worse.

What can I do so the entire sidewalk will be fixed properly?