Fraudsters are falsely claiming to be calling from the Financial Ombudsman Service (FOS) to try to persuade people to reveal details about their personal and financial circumstances - and they are even managing to make FOS's number appear on people's caller ID.

https://www.moneysavingexpert.com/news/banking/2018/06/scammers-are-calling-customers-customers-and-pretending-to-be-the-financial-ombudsman-watchdog-warns