Test recovery with unsupported parameters

> Our backup is overwritten with a corrupt backup too.

Restore from the next older backup

Most customers buy a Perpetual licence that does not terminate.  What your organisation needs to be doing is to be paying for Support every year.

As regards the ORA-600s and recovery : Your best bet is Oracle.  There are third party vendors -- search google for "DUL" and "PRM-DUL".http://www.parnassusdata.com/