A Sydney construction company boss targeted customers in a three-month "extreme course of threatening and violent behaviour" to discourage them from taking legal action over his work.

Bill Issa lobbed Molotov cocktails at five homes and businesses across Sydney and ambushed an Ultimo restaurant owner with two other men, one of them armed with knuckle dusters.

Issa beat the man severely with a metal torch while the other two laid in to the restaurateur, having cornered him while he was alone, taking out rubbish.

Issa, 53, has been sentenced to a minimum of nine years behind bars for the “campaign of fear” which began in March 2013.

“The offender wanted to send a clear message to the victims that they should discontinue proceedings,” Judge Peter Zahra told Sydney’s District Court while sentencing Issa.

Issa, the court heard, had been emboldened by the success of his initial fire bomb attack.

Before the first was thrown, proceedings were started against Issa’s company Isabella Retail in the then Consumer Trader and Tenancy Tribunal over renovations at a Maroubra hairdresser’s salon.

A five-day mediation hearing failed to resolve the issue and further action was launched in court.

While the fire bombs thrown at the salon didn’t cause much damage, they did result in the legal action being dropped.

Judge Zahra found this gave Issa ideas about how to sort out other dissatisfied customers he was feuding with.

Several other homeowners and the Maroubra hairdresser’s lawyer’s chambers were targeted.

A St Clair home was hit with a Molotov cocktail, while a family, including two children, were inside.

In June 2013, Issa’s stoush with the Ultimo restaurant owner over exhaust fans turned violent.

“The attack on the victim was an attack by cowards,” Judge Zahra said.

“The attack was ferocious.”

The owner suffered a fractured arm and lacerations to the head, the court heard.

Despite the ferocity of Issa’s attacks, Judge Zahra found he had a low prospect of reoffending.

He said Issa had no criminal record but had been found guilty of 10 charges relating to the fire bomb attacks.

About two weeks into his trial he pleaded guilty to a further charge of grievous bodily harm over the restaurant owner’s bashing.

With his sentence backdated for time already served in custody, Issa will first be eligible for parole in February 2024.