Speed of broadband on MTNL FTTH Fibre Network slows down.

Hi,
For the last 3 days, I am getting speeds of 0.2 - 0.5 Mbps. While last week I was getting 9.8 dl / 4.8 ul.
To solve out the problem myself I spoke with 2 people at MTNL. One mentioned that I had crossed the free usage. The 2nd guy mentioned getting all the joints checked between my building and the exchange.
But, I checked and found that I have not crossed the free usage limit and I am still under it and it is not possible for me to go out and check all the joint from exchange to home.
How to deal with the problem? Is there any solution?

Hello friend,
Can you tell me that, Do you have actual FTTH or VDSL? What kind of cable comes in to your modem?

If it is a VDSL than your problem can have a solution otherwise you are being cheated on the name of FTTH.