She wrote the cheque they then cashed at the bank.
The next morning they came back to her house and cut a rectangular hole in her ceiling, before fleeing when Leonard's neighbour arrived and began asking questions.
Leonard said she had lodged a complaint with police. However, police are yet to confirm this to the Herald.
A neighbour - who did not wish to be named - said the 82-year-old was a perfect target for the scammers because she was "very trusting".
"If someone tells her a story, she will believe in the goodness of their hearts," he said.
He said Leonard - whose children lived overseas in Berlin - was not rich and could not afford to lose the money.
"She's 82, and what seems like a reasonably big amount to a younger person is shattering to her," he said.
The three men appear to have also combed the neighbourhood.
Nearby neighbours of Leonard's, Des Carville and Fale Opapo, said the men also knocked on their doors.
Carville told the men he didn't need maintenance work because his house was a state home and Housing NZ did the repairs.
Another older couple further down the street said a man knocked on their door a month earlier, saying he had noticed two tiles had fallen off their roof.
The man promised he could fix the tiles for less than $900. However, the couple wondered how he could quote a price without taking a closer look and so contacted their regular roofing company Solar Chem Roofing for advice.
Solar Chem Roofing sale representative Roly Swann said he had heard numerous stories about scammers and called them a "blight" on his industry.
He said he was contacted in December by the family of another elderly woman wanting advice after she was duped out of more than $10,000 by two guys with Irish accents.
He advised residents approached by strangers to always ask for identification and proof of a worker's qualifications or business and to also contact the Roofing Association of NZ if in doubt.
Leonard's neighbour said the men that scammed his elderly neighbour had been confident, alert and agile.
He first noticed a problem at Leonard's house on January 4 when he saw a tile out of place on her roof.
After the men left, he went to talk to Leonard and discovered she had given them money.
He said the fake tradesmen were so successful in tricking Leonard because they were able to play on a belief she already had that her roof was leaking.
The neighbour then phoned the police, who told him to immediately call back if the men returned.
When the tradesmen returned the next day, they began cutting a hole in Leonard's ceiling, until her neighbour noticed and came over to check what was happening.
"When I knocked on the door, and this guy opened it, he was very alert, very confident," the neighbour said.
"He had answers ready on the tip of his lips."
When asked for identification or a business card, the two men present said it was in their car. But instead of coming back with their identification, they fled.
Leonard's neighbour suspected the men had returned on the second day to try scam more money.
The police arrived shortly after, saying they had tracked the car's registration to a motel but that they had not yet made any arrests.
