TalkTalk customers in the North have been targeted by scammers.
A fraudster removed money from one bank account after claiming he was from the company and the victim's computer was running slowly, the PSNI said.
After he gave them details the thief also tried to make online purchases using the bank card.
During the call the imposter told the victim he would be due a refund of £200 (€250) and a list of banks appeared on his computer screen.
He was asked to select his bank.
He was kept online until he confirmed further details that allowed the perpetrator to remove money from his account.
PSNI Detective Constable Stephen Crooks said: "I would advise that the public should be aware of this scam and if someone asks you to press the 'Windows' key and the 'R' key on your computer and/or asks for your banking or payment card details terminate the call immediately and report the matter to Action Fraud either by phone at 0300 123 2040, or online at http://www.actionfraud.police.uk/."