What to do to make correction in challan of income tax

Respected Member Friends,

One of my Client paid Rs.25,000/- as IncomeTax by a manual challan. But by mistack he Specified Assessment Year as 2010-11 instead of 2011-12. Further the return for AY 2011-12 was Filed by way of E-Filing.

Now, I wants to know the Correction Procedure for the above mentioned Mistake. Can you Please Provide me Proper Procedure of it. Waiting for your Replyyyy.........

Shyamsingh D Rajput