BSNL Combo 500 Home — Billing Errors

6 months back i availed BSNL broadband with telephone connection of Rs 500 scheme.
I used to get charges around 560 to 650 rupees including call charges and Broadband charge.Total call was around 150 to 200.
But this month i got bills for 810 calls stating Rs 1275.
My connection is only home purpose.
We asked call list,
But BSNL is giving Mobile number list and 95 Number list only. Even the call list says i made only 57 calls of mobile and 95 numbers.
They are saying no land line number call list is readily available.
I am sure in my home we have not talked for 810 calls, because 2 Cell phones are existing and we always using cell phones.
(810 calls means atleast 10 hours talk minimum for a month, it is highly difficult in home environment to talk for 10 hours )We actually got the BSNL line for broadband purpose.
I talked to BSNL, there is no proper reply.
What can i do..
I am thinking of closing the BSNL connection.
Give the advise.
To whom we can appeal ?
Can we get early disposal?