one of my friend had called up 12540 and they had said yesterday that there is nothing wrong from their end and it might be a localized issue, but what is weird is this is happening at 10.45 am.. and goes on till 12 am.. then the usual speed is coming.. and this happened on sat too..i am on the 182 series too but i get full 9.8 on vdsl.
this seems to be a problem at the local exchange .
may be they will come to work tomorrow and hopefully solve it.. but overall usual day's its working fine.. but i am still unable to understand why it's happening at the exact time