Ownership Change

So, I had applied for Ownership Transfer of the BSNL SIM that I use which is registered on my father's name, to my name. Regarding this they had to disconnect the the services of the SIM and a new SIM will be issued under my name. The SDO from the BSNL office said, I have to pay a sum of Rs.800 something as BSNL's charges and recharge Rs.249 to use the services. My query is that, if the number is same and the transfer is happening from Father to Daughter, why are they charging so much. Secondly, the existing plan of that number should be carried forward as the number is gonna be the same. Does anybody have any answer for this? My friends are saying no charges should be levied and plan value should be carried forward, I'm confused, am I being scammed?