For Free version
On the following page you can download the latest hot fixes: http://www.gemboxsoftware.com/spreadsheet/free/GBSBugFixesFree.htm.
GemBox Software does not provide technical support to the users of the Free version. To purchase the Professional version (which comes with technical support) go to: http://www.gemboxsoftware.com/spreadsheet/pricelist.
For Professional version
If you are user of the Professional version look at your SupportProfessional.htm page in the component installation folder.