Where HOA and owner draw the lines over street work?

I live in a 6-plex condo. The 2 center up & down stairs units join sewer systems "outside" the building into 1 pipe going to street. I paid for a camera to identify hole in exit pipe 3 feet from building. The Property Manager,  United Community, our HOA associations said "Sadly this is a neighbor to neighbor issue". I understand everything inside is mine, and outside to the street is their responsibility. How can I pull up the neighbor's pavers and fix this? Shouldn't this be the responsibility of our Association?