Not from "Firefox" or from Mozilla!

Mozilla doesn't use telephone number for contacts of any sort, there are no resources for direct human communication with users.

You should always contact your bank directly by phone or via its website in case of questions. Your bank would never ask you to provide personal data in the way you described.

If you get a pop-up message asking to update Firefox or plugins or scanning for malware or other message about personal data then such a message is likely a scam and you should NEVER respond to such an alert to avoid getting infected with malware.

• only update Firefox via "Help -> About" or by downloading and installing Firefox from the Mozilla server and never via a pop-up or link on a web page.
• plugins should only be updated via the plugin itself or by visiting the home page of the plugin.

See also:

• https://support.mozilla.org/en-US/kb/i-found-fake-firefox-update