Tax demand 143 1 a

I had filed my tax return and paid all taxes through self assessment after set off of TDS as per 26 AS.

but I received intimation under section 1431a - raising a demand of around 23,000

I noticed that effect of TDS for 23,000 was not given though it was reflected in my 26 years

so I immediately through web portal replied 2-3 times for the correction.

but no response and the demand is still shown as outstanding and they have also added interest .

so what should I do?
is there a provision of making 154 application through web portal ?

would request for your valuable advice