Assuming you have support, you just need your NOW account associated with your company and your filer serial numbers. Use the serial numbers to open a non-technical case to work through whatever account issues are preventing you from opening a technical case.
On the subject of upgrades, there are many considerations coming from such an old release in a production environment. Its not something you want to attempt on your own if you are new to the NetApp platforms. Professional assistance would be a very good idea (to be clear, I work for a professional services organization).
If you go it on your own, make sure to get upgrade advisor reports and thouroughly review the upgrade/revert guide for your target version. Coming from 8.0.2, look at moving both arrays to 8.1.4P8. Pause there and carefully evaluate the impact of other components in your environment before going to 8.2.3P1. You will want to become very familiar with the IMT as it relates to everything else you have touching the arrays.