What additional information would I need to provide for EEOC to reconsider their pre-determination

I was fired for falsifying my timecard (gross misconduct). At phone hearing with OESC, I learned my boss falsified my time card and fired me for it. I filed a charge of retaliation with EEOC and their pre-determination states it is unlikely the agency will be able to establish that a violation occurred.
I gave them incidents of reports by myself and two co-workers where boss used innappropriate behavior, which made us feel uncomfortable. Also stated incidents where I asked boss about the raise he offered to accept another position in the company; and where I asked to return to former position without the increase. At mediation settlement, the company states there is no record on file of the inappropriate behavior and no emails were found regarding the raise. I am trying to get co-workers to write letters for me, along with another manager who was present at the time of the position change. However, they are reluctant to help. Is there anything else I can present to help my case? What can I do?