The only thing I can think of is to try the User Agent Switcher extension for Firefox:https://addons.mozilla.org/en-US/firefox/addon/59
You can switch the user agent to tell a website you are using IE and perhaps then the function will work at your ISP's site.
No guarantees, as your ISP may be using some non-standards based IE functionality (ActiveX, etc.) for the page functions. I know quite a few of my employers employee-only sites are tough to navigate or pop warnings about me using the wrong browser when I use Firefox on them.
Not a problem with Firefox, the problem is the ISP's use of non-standards compliant technoligies.