Older people and carers have been told to beware of scam retail or investment operations targeting the elderly.

The Insolvency Service said that in the three years to March it closed 78 rogue firms in England and Wales, which had scammed £28m from nearly 2,000 victims.

Firms had aggressively cold-called or door-stepped older people and then overcharged them or failed to deliver.

Scammers targeted “the most susceptible members of society”, most of whom never made good their loss, a spokesman said.

“The worst aspect is the callousness with which the fraudsters go about their business; ignoring the obvious fact that that because of their age, most victims will never be able to make good their loss,” head of investigation and enforcement Robert Burns said.

“If you are cold-called, don’t be afraid to say ‘no thank you’. If in doubt, you should take time to research the company and get some independent advice.”

The Insolvency Service is a statutory body that deals with financial failure and misconduct associated with it.

It said 49 of the 78 rogue companies sold land for “building” that either did not exist or was on protected land.

Others ripped off their victims over fine wines, fire alarms or worthless plots of land. All targeted older people, pressure-selling over the phone or with a foot in the door.

One pensioner lost tens of thousands of pounds from being tricked into parting with historic gold coins, the service said.

The Insolvency Service said many more scams have not been stopped and warned people to be on their guard and to ask for help.

It said often the same rogues would move on and set up multiple operations, seeking out vulnerable members of the public.

‘Too good to be true’

Business Minister Norman Lamb said the scammers exploited older people’s trust and urged people to be vigilant “when approached to make investments out of the blue”.

Michelle Mitchell, from Age UK, said that “the sad fact is that if something sounds too good to be true then it probably is”.

“If you feel under pressure to commit, then just step away because any reputable company will allow you time to think an offer over.”

She said Age UK had produced two guides to advise older people on how to protect themselves from scams.

The Alzheimers Society said that it was campaigning against the financial abuse of dementia sufferers who it said could already be “struggling financially due to the huge cost of care”.

“Everyone from banks to the general public needs to work together to stop these scams and help protect those who need it most,” chief executive Jeremy Hughes said.

The warnings come on World Elder Abuse Awareness Day.