If you are using Kayako version 3 (i.e., eSupport 3.70) and you want to upgrade to version 4, we are sorry to inform you that this is not possible as there are no scripts available to migrate your data from version 3.
If you wish to use the newer version of Kayako, you are going to have to start fresh with a new Kayako Classic subscription. You may keep your version 3 instance as an archive for reference.
If you wish to do so, please contact Sales by sending an email to Sales@kayako.com.