I keep getting the dreaded "there was an error" error when I go to manage my booking on the website



On the JB app, I can see the booking but when I try to "manage" it, it does nothing. I tried incognito/clearing cookies and nothing.. I've also called and they told me everything looks good, so they don't know what the problem is.
Is there a way I can change my ticket online? The fare I want isn't available on the phone so looking for options.