Tds late payment and non-payment of interest on tds

Hai friends...........

           This is paramesh from Visakhapatnam................. Friends i had a doubt ragd. to TDS Interest........

 Problem is My company is deducted TDS and paid lately and without any interest. They filed TDS quaterly returns also..... Now they got a notice from IT Dept. In the letter they mention that amount must be paid with in one week otherwise we need to pay with simple interest. Now my question is:

1) What is the simple interest rate?

2) There is any need to file a revise-TDS Quaterly return.