When opening SBI Demat account, apart from address proof,my bank pbook first 2 pages copy is necessary.>?

For address proof,I will submit telephone bill/ration card,but the address mentioned in my pbook is different from that of telephone bill/ration card. Is it necessary to get old address changed in my pbook? I dont have sufficient time to change address because bank is far from my residence and I will be out of station where I can open Demat A/c. There is limited free period offer for opening SBI Demat A/c. How much money can I save by this offer.Will I save annual charges or registration charges only?