The number of conmen trying to double-dip at the expense of elderly victims is on the rise, council have warned.

In recent weeks at least two people who have previously been conned out of thousands of pounds by rogue traders have once again been targeted.

The first was a retired Waddon resident who last year fell victim to roofers that took upfront payments of £13,000 but then failed to carry out any work, was approached by a man offering to clean his gutter for £10.

Removing roof tiles, he told the householder that repairs were needed, and that they would cost £15,000. Independent inspection showed that minimal work was required.

The second case involved an 83-year-old person who had previously been conned by a builder that had taken thousands of pounds in payments from her over the years, in return for minimal amounts of work, was revisited recently by the builder who declared that he was going to finish the work on her roof.

He was told that no work was to be carried out. However, two months later, three young men claiming to be from a roofing company called at the house and caused damage to the outside of the property.

Croydon Council's trading standards team is concerned by the rise in these types of cases in such a short period of time.

Council’s executive director with responsibility for safety, Shifa Mustafa, said: “It’s a known fact that gangs of scammers and rogue traders swap information about addresses at which they have successfully conned householders out of money.

"In some cases this amounts to thousands of pounds – money they’ve saved over many years with a view to financing their lives during retirement.

“To go back and target those people for a second time is reprehensible, and can leave the victims genuinely traumatised – fearful for their safety in the home they’d always considered safe.

“Our advice is that nobody should ever employ cold-callers who say they’re able to do whatever job they claim to be urgent at a cut-price rate.

"Always get three estimates from reputable companies for any work. And, if you’re unsure, ask a relative or friend to be present when traders, who you’ve invited, call to price the work.”