It's common knowledge that consumers can claim from their credit card provider in the event of a problem with their purchase.
But less well known is an obscure Visa rule which means that debit card transactions are often covered too.
Called 'chargeback', the process has been agreed to by all banks issuing Visa debit cards.
Unfortunately not all bank staff have been trained about its existence, so some customers have told us they've had problems making claims.
It works by the card issuer charging back the value of a problem purchase to the retailer's bank.
Once recovered, this cash can then be passed to the consumer.
On today's Working Lunch we featured two viewers who'd bought new Rover cars earlier this year.
Whilst happy with their cars, they were concerned that Rover would no longer be able to honour the warranties.
And worse, Barclays, who they both banked with, claimed the value of the car warranties was unquantifiable, and so ineligible for chargeback.
Mercifully, after some footwork by our pair, a helpful Rover salesman disagreed.
And armed with a price tag and with a little help from Virginia, the bank finally conceded they were due a refund.
As Virginia says: "Only when the word chargeback becomes familiar to consumers, will the banking system get used to dealing with it."