Log in fail breaking page

Have just spotted a glitch on a log in page - if the incorrect details are entered the page gets messed up when it reloads after an invalid username and password.

I suspect its because of a URL rewrite on the page, but I can't get the fail redirect right.

The page without the rewrite is here:

http://www.safariawards.com/africa/index.php?GSG_URL=zarafacamp

(Which is screwed up too, but not so much an issue)

With the rewrite, the URL would be:

http://www.safariawards.com/africa/zarafacamp/

Which is fine. But if you try any random username and password to log in, it gets messed up.

The success redirect URL is: "successRedirect" => "../africa/".$_SESSION["GSG_URL"]."/",

And the fail redirect is currently the default one: "failRedirect" => "index.php?failedLogin=1",

Based on that what should the fail redirect be to reload the page correctly?

Thanks.

(I've attached a copy of the page just in case.)