I just discovered my 80 year old father was ripped off by an IT phone scam.

You can sue for the return of the money on the basis that the contract was induced by fraud, or that your father lacked the capacity to contract, but from what you've described it sounds like a scan where you will not be able to locate the caller and/or the caller will have no money to repay your father.  You'd probably have better results going to the police and/or consumer protection agencies, or even one of those consumer advocate reporters whom many television stations employ.