Merton has dealt with nearly 50 complaints of online and postal scams in the past year.
The scams, such as fake lottery wins, bogus inheritances and get rich quick schemes, appear to be increasing.
Trading standards officers say scammers target the elderly and vulnerable in mass marketing campaigns that guarantee prizes if an order is placed for goods.
The council says one resident had been giving money for six years until officers intervened. Another was contacted by a 'clairvoyant' who used public records to dig up information on the resident.
Ross Garrod, Merton Council’s Cabinet Member for Street Cleanliness and Parking, said: “These companies are totally unscrupulous and, once they get a response, will bombard people with future correspondence.
"It’s unpleasant and manipulative but scammers conned people out of more than £3.5 billion in the UK last year.”
For more advice, ring the Citizens Advice Consumer Service on 03454 04 05 06.
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