Need to track changes and audit in R12 ,critical values updated by "anonymus" and back dated

Hi,

We have a serious problem and need suggestions to track the same in oracle apps R12.

We have created the PROD instance in DEC 2012 and loaded the Chart of accounts values(Say 500) and taken a backup.

We have our UAT instance with Chart of accounts values (Say 3000) and this includes junk values.

Now to our surprise we see that apart from the 500 values in PROD ,the 3000 values from UAT is also loaded in PROD with a back date of MAY 2011 and updated by "ANONYMUS".None of us have loaded the values from UAT instance and now all junk values from UAT ar ein PROD .