Please Help: income tax

Assessee filed his return for the A.Y 2012-13 on 30.7.2012,he is by mistake claim advance tax 100000 but actual advance tax paid by client rs 200000. further his case was selected for scrutiny and A.O not consider the Excess Advance tax paid. and assessment under 143( 3) is final, now assessee can claim the full advance tax by what manner.