P.C. Chacko, chairman of the Joint Parliamentary Committee investigating the 2G scam, categorically stated on Thursday that the Comptroller and Auditor General of India had exceeded its mandate and made policy prescriptions which were the prerogative of the government. Mr. Chacko told reporters here that the concept of presumptive loss raised by the CAG cannot be justified and arithmetic jugglery cannot substitute facts. While he had high regard for Vinod Rai, the former CAG, he said he disagreed with him on the 2G findings.