Taieri Age Connect is based in the Mosgiel Senior Citizens Hall and offers information and social activities to people aged 55 and over.
The hall is in Hartstonge Ave, beside St John and near the Mosgiel Memorial Garden and library.
Last year, the windows at the rear of the building were broken twice.
The windows were initially cracked in November and when they were fixed in December, they were smashed later that day.
Both incidents were reported to police.
Taieri Age Connect president Trish Didham said it was frustrating people would purposefully damage their building.
"Why are they attacking old people’s rooms?" she asked.
The first sign of damage was the cracked windows on November 12.
Then a few days later, members were having a meeting, when they noticed two young people throwing objects at the window.
"Two of the ladies ran out, but of course they disappeared into the trees," Mrs Didham said.
About 15 minutes later the young people walked past again with their hoods down, which was "just so blatant".
About a month later, after insurance had been claimed, the windows were replaced.
"It must have been in the morning because then one of our committee members came down at about 7pm and she ... realised that they’ve been re-broken again."
That time a brick was thrown right through the window, which also damaged the frame.
A security camera was installed in the gardens last year but did not cover the hall.
A Dunedin City Council spokesman said one window in the library was damaged as a result of suspected vandalism sometime on or around New Year’s Eve.
Mrs Didham said she thought better lighting in the "dark" walkway between the hall and library would deter people from damaging property, so wrote to the Mosgiel-Taieri Community Board asking for its support to get a new light installed.
"That might help because half the problem is it’s easy for them to sneak around in there because it’s so dark."
She also completed a council "fix-it form" to have the trees and plants in the walkway trimmed.
At last month’s community board meeting, chairwoman Joy Davis said council staff agreed to upgrade a light on the corner of the library and position it on a more suitable angle.
Board member Martin Dillon said the overgrown vegetation made it an easy place for people to hide in and get up to mischief.
"That needs to be cleaned up before the lights go in because the lights will be covered by shrubs and trees," Mr Dillon said.
Fellow board member Brian Miller agreed, saying he had spoken to residents, who said it was a daytime issue.
In a letter, St John, which the group shared the hall with, agreed to install a sensor light at the hall’s main entrance and a security camera and sensor light at the northwest end of the building, Mrs Davis said.
Council parks and recreation group manager Scott McLean said staff looked at the vegetation trimming with contractors and it was programmed in their system.
Extra lighting in the walkway was outside its budgeted work plan, he said.
Mrs Davis said she had encouraged the group to make an annual plan request to the council.
