Just found out something new.
This now seems to be a billing mistake/blunder on Hathway's part.
My plan is a 512-Intropack (2 months validity), as i said before.
my current plan renewal gives me a validity period of 1-aug-2008 to 30-sep-2008
But Hathway has happily sent me a bill dated 1-Sep-2008 for Rs. 430(??)
This could very well be someone else's usage debited to my account
(I trust these ppl very much to make such mistakes and not bother to check it within the organization first before bluntly cutting off the customer, asking to pay the amount)
Sorry if i'm pulling this thread too long....

i hope it helps someone who is facing a similar issue or someone who opts for Hathway's services