You should complain to your Bank. Firefox Releases are well published and any software developer should be aware of the Release dates and able to update their software to work with the new Releases. Pre Release builds of Firefox are available for anyone needing to test them and ensure their software is updated to remain compatible with Firefox.

Hi, unfortunately Trusteer is seemingly often slow to accommodate the latest version of Firefox, which is a pity, because using an old version can in itself compromise your security.

http://www.trusteer.com/support/supported-platforms

Details of new Firefox versions are available well in advance - https://wiki.mozilla.org/RapidRelease/Calendar

Unless your bank insists, you don't of course have to use it, but that's a matter of personal choice.

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Trusteer claims they support Firefox 52 and although they do not mention Firefox 52 ESR you can still give the latest ESR version Firefox 52.1.0 ESR or Firefox 45.9.0 ESR a try.

You can install a portable (ESR) Firefox version to access websites that do not work with the current Firefox release. The portable version comes with its own profile folder and doesn't interfere with currently installed Firefox versions.

• http://portableapps.com/apps/internet/firefox-portable-esr
• http://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./
• http://www.freesmug.org/portableapps:firefox#toc1
• http://portableapps.com/support/firefox_portable#helper_apps

You should create a new profile if you would use the ESR release instead of the portable version.

• https://www.mozilla.org/en-US/firefox/organizations/all/
• https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles