Short deduction of tds on salary

Friends,

You must be aware about the defaults generated by TIN NSDL Site these days. I am facing the same problem. I've a query, kindly help me solve it.

A company has short deducted TDS for one of its employee & the same had been paid by the employee as self assessment tax. Now the IT dept. has sent me a demamd notice u/s. 156 of IT act, 1956.

Now my querries are :

     1. Is the company bound to pay the demand? 

     2. If yes, then is it not double tax collection by the tax authority?

     3. Is there any remedy for the same?

     4. If no then kindly quote some case laws.

I'll be thankful to the members for their views and help.