Victims are lured in by the promise of money or large rewards, but first they have to pay small payment instalments, allegedly for costs such as insurance and postage.
The scams could be for fake lottery wins or fraudulent banking transactions.
The latest one, reported by a Maidenhead resident, involved the sale of puppies from Scotland via a seller in West Africa.
The victim was asked for an initial down payment for the puppy but this was followed by more and more requests of money supposedly for courier fees, inoculations, insurance and a carrier crate.
When the scam was uncovered £650 had been paid out. The money could not be recovered as the cash was withdrawn from a money exchange service in Cameroon.
A Scottish address was also used in the scam but that, along with the name of the seller are believed to be false.
Trading Standards advise against using money exchange services for any payments except to people they know and trust.
In addition to Trading Standards and Thames valley police, frauds can be reported to Action Fraud on 0330 1232040.
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