Options for obtaining SSG550 Software

Apparently the SSGs we have, which were purchased before I took over, are not registered to our company and as such we are unable to purchase support to get access to software downloads.

Does anyone have any suggestions as to a route we could take to obtain software? Upgrading to a newer platform is not feasible at this time due to the size of the configuration (4500+ lines) and man hours it would take to convert.

Thanks!