Security releases for Joomla 1.5.24 & 1.7.2 has been released.
Read more & Get it at the following links:
For 1.5.24
joomla.org/announcements/release-news/5390-joomla-1524-released.html
For 1.7.2
joomla.org/announcements/release-news/5389-joomla-172-released.html
or use the update feature inside your Joomla administrator
You should be able to turn them off. To be sure you could always download the htaccess files to your local computer through ftp or cpanels file manager and then reupload them (except the # -Front Page- one) if needed.
Welcome to the forum, LondonPC.
As far as I know, it should be instant. But if you haven´t received it, please open a ticket with the help desk as Alex suggests and they will help fix this.