From Drupal 7.15, I haven't seen anymore the button to update the installation.
I had to update my websites manually. Is it a known bug from Softaculous?
Sir we have tested this on our servers and it works fine, it also displays an option to upgrade Drupal from 7.15 to 7.17
I have attached a screenshot of the same.
Can you please check what is the version of Drupal available on your server ? Also can you please open a support ticket with your account details we will check it.
https://www.softaculous.com/support