In short: reporting fraud means telling your bank and the competent authorities what happened as quickly as possible — to stop the payment, trace the money and protect other people.
Simply put: Four steps: Stop (don't pay a second time) · Block (the card or app access) · Tell (your bank on its official number and someone you trust) · Keep (screenshots, account numbers, dates; don't delete the chats). Report even if you lost no money — you protect others.
Example: You sent €600 to a fake seller. You call your bank within the first hour, report it to the police and attach screenshots of the chat.
Watch out: shame is the fraudster's ally. Reporting is not a failure — "straight away" is the fastest cure.
Example: Bulgaria — first the bank; for a crime — the police and GDBOP (General Directorate Combating Organised Crime, Cybercrime Department, cybercrime.bg); companies and licences — FSC and BNB; disputes with traders — CPC; personal data — CPDP.
Check in your country — your bank, the police (often with an online cybercrime form), the financial supervisor and the consumer protection authority.
Source: Europol — Online fraud schemes: https://www.europol.europa.eu/crime-areas/online-fraud-schemes · GDBOP cybercrime: https://www.cybercrime.bg · CPC: https://kzp.bg