Itr ay 2011-12 needs correction

Hi,

I received a demand notification from IT in 2012 to pay approx 7K.  Upon checking I realized I had wrongly filed my ITR for AY 2011-12. I entered the wrong amount in the "income charegeable under head of salaries". I entered 2.89Lakhs instead of 2.07L. My form 16 rightly suggested a tax of rs 585.  where as the demand notiof U/s 143(1) demands Rs ~7K based on the wrong entry. How do I get this corrected?   I have already responded as below.  Kindly advise.

Regards,

Sreeni