Francisco Guerreiro, I am not sure which email you are referring to. Most likely that was the email informing you that 1.6 is now available and if you would like to you can update your software.
However it is always UP TO YOU to update or not. Even if you've clicked on "Update" link in your admin panel, system should have asked you ONCE MORE whether you are sure that you want to update or not.
Oxwall never forces admins to update their sites.
Now that your have updated your site, there isn't an easy way to go back.
1. You can restore your site from the back up.
OR
2. Fix current issues and keep 1.6 version.
I will be glad to assist you with your issues, but you need to provide more detailed information on what is not working.