A building society cashier "living beyond her means" targeted vulnerable customers and stole thousands of pounds from their accounts.
Helen Day, 47, worked for Nationwide and withdrew money without authorisation from the account holders.
Police said the three victims were vulnerable because of age, degenerative diseases, or both.
Day, of Chatteris, Cambridgeshire, was given a 12-month prison sentence, suspended for 18 months.
She admitted three counts of fraud by abuse of position at Peterborough Crown Court.
Day, of Tern Gardens, worked for Nationwide for 16 years, but between February 2017 and January 2018 used the personal information of her victims to answer their security questions, Cambridgeshire Police said.
The offences came to light when one victim flagged up a suspicious £2,000 withdrawal.
'Brand new kitchen'
On the same day, Day left work but returned shortly after and deposited £1,000 in £20 notes into her own bank account.
Day was interviewed by Nationwide investigators in March 2018 and denied taking the cash but did not provide an explanation as to where the money had gone.
She resigned a month later but the building society's investigations found transactions totalling £7,860 from three victims, with all the withdrawals from either the Huntingdon or Ramsey branches.
Police then searched her home in July 2018 and said she "was living beyond her means, with a brand new kitchen, brand new iPhones and high-end electrical goods".
Det Con James Howard said: "She betrayed that trust by acting as a helpful cashier while stealing thousands of pounds from them.
"Nationwide have also reimbursed the victims and have recovered their losses from Day's company pension."