Seven staff at an emergency plumbing firm, which charged extortionate prices and bragged about it on WhatsApp, have been sentenced.
Trading Standards received more than 150 complaints about Faster Response Limited, later Prestige Property Solutions, between 2016 and 2017.
The men sent messages mocking their victims, Leicester Crown Court heard.
Leicestershire County Council said it was "despicable fraud perpetrated across the country".
Three men were jailed while four men were given suspended sentences.
Trading standards began investigating Faster Response Limited in March 2016 and it featured on Watchdog in 2017 before being shut down.
But the company - led by Russell Canfield and Liam Cuffe - continued to trade with the same staff under the name Prestige Property Solutions. Both firms were based in Kirby Muxloe, Leicestershire.
Prosecutor Adam Pearson said the seven men would, after advertising OAP discounts, charge "often infirm" customers up to 10 times the correct amount for simple plumbing jobs.
He said during the 15-month investigation, more than 150 complaints were made and their turnover would have "exceeded £1m".
A search warrant was executed on Prestige Property Solutions in August 2017.
Mr Pearson said a 92-year-old woman was quoted £3,000 for a £452 job and told her bath would have to be smashed in the process.
In a WhatsApp exchange, plumber Leighton Costello sent a picture of a £11.89 receipt for parts while the customer was eventually charged £1,200.
Mocking the customer, he wrote: "That is what you get when you up sell lads."
Who were the convicted men?
- Russell Canfield, 44, of Elsalene Drive, Groby, was jailed for 40 months for two charges of fraudulent trading
- Benjamin Molloy, 33, of Laxton Close, Melton, was jailed for 27 months for two charges of fraudulent trading
- John Stott, 38, of Corporation Road, Ilkeston, Derbyshire, was jailed for 24 months for two charges of fraudulent trading
- Stephen Rice, 46, of William Street, Nottingham, was given a 15-month suspended sentence for one charge of fraudulent trading, and will have to perform 200 hours of unpaid work
- Richard Jones, 38, of Glen Park Avenue, Glenfield, was given a 15-month suspended sentence for two charges of fraudulent trading, and will have to perform 200 hours of unpaid work
- Zackary Morgan, 21, of Borrowcup Close, Leicester, was given a 15-month suspended sentence for two charges of fraudulent trading, and will have to perform 200 hours of unpaid work
- Leighton Costello, 27, of Cart Crescent, Leicester, was given a 15-month suspended sentence for two charges of fraudulent trading, and will have to perform 200 hours of unpaid work
The defendants exchanged messages while watching the Watchdog broadcast in July 2017 about Faster Response.
One of them wrote: "Says we've been ripping off pensions [sic] for years lol."
Russell Canfield replied: "I know that's wrong mate its everyone we ripped off not prejudice of age lol."
Leicestershire County Council's head of regulatory service, Gary Connors, said the men "all had their part to play in an emergency callout business which was set up from the outset to extract substantial sums of money, primarily from the elderly and vulnerable".