Service tax penalty

Dear sir/Madam,

I have an doubt regarding Penalty leavied for late filing of Service tax. 

As per the Notification, the penalty for late filing has been increased to 20,000.

In one of my case, the client is in deafult for non filing of ST returns for the FY 2009-10 and 2010-11.

But, the levy of penalty was only Rs. 2000 in those FY. 

I am filing the returns of FY 2009-10 and 2010-11 now. 

My doubt is, whether the Notification has a retrospective effect??? Do the Client have to pay Huge amount of Penalty??

And which one is better?? To file Online or Manually???