The only problem i had with MTNL was the horribly slow speed they provide and no matter how much i paid they would not be able to provide more than 1.5 Mbps to me. Funny story they have increased the speeds of all connections to 8 Mbps but that is pure s**t because they do not plan on improving the lines to ensure everyone gets the increased speeds.
After years i found that if you call the zonal/nodal something officer and complain they sort your problem out within a day.
I was paying Rs. 1000 for 2 Mbps (40 GB) after FUP 1 Mbps(~900Kbps).
It is like MTNL does not care because their losses are being paid by the government and the employees get their salaries and retirement money regardless of losses being registered.