Unregister a vCenter extension with a space and special character in the name

I'm unable to unregister the vCenter extension ["EMC Avamar Backup & Restore"] .  If I paste it in the UnregisterExtension, I get 'InvalidArgument' .  I also can't click on the extension in the browser.  I get a browser error when it tries to navigate to ..../mob/?moid=ExtensionManager&doPath=extensionList%5b"EMC%20Avamar%20Backup%20%26%20Restore"%5d , err_empty_response.  I believe both are related to the spaces or the & in the name of the extension.  Does anyone have ideas?

thanks