gas connection transfer with in Delhi

Location/place: Dwarka,New Delhi

Name of company/service: Jai Jawan Gas Service

I got my gas conection transfer from Moti Bagh to Jai Jawan Gas service. On transfer I was told to furnish Gas Transfer voucher, Identity proof and address proof.For Identity proof I submitted PAN photocopy and for address proof,my land line duplicate bill. when I approach owner of gas agency, he wanted that telephone bill must have paid stamp of MTNL.I informed him that tele bill is my name, gas is in my name, PAN for identity, my photograph is on transfer voucher then why should I get my land line bill stamp. Not only this when I had approached them on 24 Jul 12 for transfer, that day they had seen all papers and told me that it would take 3 days to transfer and come back on 27 jul12 evening or 28 Jul 12 morning. That time they did not mention that tele bill need to be stamped.When I apprached them on 04 Aug 12, now he wants my bill to be stamped by MTNL.
My comlaint is that why should I give them stamped land line bill. Bill which I provided was of Jul 12.This is a harashment to consumer. why should not duplicate bill should act as address proof.