Davia Gibbons had been under the threat of a suspended prison sentence imposed just weeks earlier for a carbon copy crime when he committed the offence.
The 31-year-old, whose Wolverhampton-based business was called 1st Choice Roofing, pleaded guilty when he appeared at the city's Crown Court on Tuesday.
He admitted a charge of fraud by false representation by adding £750 to a bill by claiming to have found an additional – non existent – 'problem' while repairing the roof of a house in First Avenue, Low Hill in April 2011.
He committed the offence just a month after receiving a suspended jail term for eight charges involving misleading trading, fraud and threatening to cause criminal damage. A building expert, who later inspected the premises, concluded: "I can only suggest that the trader was dishonest in his advice to the home owners as a result of which he obtained an additional £750 without justification."
Gibbons, from Cornfield, Pendeford, also admitted engaging in aggressive commercial activity during a row over the cost of repairing a house in Fifth Avenue, Low Hill, in May and June 2012 in which he threatened to 'send the lads round to rip off materials incorporated in the roofing work' unless the bill was paid in full.
The crimes have all been uncovered by Wolverhampton Trading Standards investigators who believe he is a serial rogue trader.
Gibbons was remanded on bail until May 1 when he will be sentenced after the latest case has been opened in full.
The rogue roofer had previously preyed on vulnerable pensioners by overcharging them for shoddy work on their homes when his business was called Tradeside Home Improvements Ltd.
Mr Sham Uddin, defending, said at the time: "He accepts full responsibility and is remorseful."
Gibbons was given100 hours' unpaid work and told to pay £5,000 costs and £780 compensation, and a 12-month prison term, suspended for two years, is likely to be activated when he appears for sentence on the latest matters.