Congrats so you got it working. Nope That was a one time installation fee & not refundable.
Looks like I jinxed it by posting about it on the forum. After 5 days of running fine, the same problem started even with the BSNL modem yesterday!!!!
But for 5 days it was super stable. I hope it was a one time problem & not the same issue I had earlier. Anyway, I talked to MTNL guys again today.
They said they will change the port - I asked them what that means? They weren't very clear.
BTW Was any of the posts in this forum helpful in getting the BSNL modem running.

If I remember correctly essbebe & I had given you some inputs
Actually, I didn't go through it. I had already tried the settings on my own earlier but it didn't work. I went through everything again & I probably changed some one thing which made it start working.
There is still one setting which isn't correct - the
ACS TR-069 settings - the fields in the BSNL Modem & the MTNL modem don't exactly match - there are some extra fields for which I don't know the values. So I disabled ACS. I will try the TR-069 settings this weekend.