Pop-ups do not diagnose a PC
A web page that says the computer is infected and demands a phone call is not a trustworthy scan result. Close the browser if possible; do not call the number or install the offered tool.
Protect accounts from a separate device
If someone had remote access or you entered a password, disconnect the affected PC from the internet. From another trusted device, contact the bank when money is involved and change important passwords beginning with email.
Preserve useful details
Write down the phone number, website, app name, payment method, and approximate time. These details help determine what access may have occurred.
Avoid stacking security products
Installing several cleanup or antivirus products at once can create conflicts. Update the trusted security software already in use and arrange help if warnings or redirects return.