termination advice

i handed my 1month notice to my employer last sept.15 and she refuse to accept it because she wants me to wait my replacement even i dont agree. and i sent a copy without her sign to the immigration dept. last sept.17..my last working day w/ her is on oct.15, yesterday oct.8, my agency called me, that the letter i sent to immigration dept. is black&white because there's no sign of my employer. My agency will write a new teemination letter for me to sign and send to immigration but i don't agree w/ it. And to wait my replacement because 1month more to come the visa of my replacement in their agency. Agency told me that if i really want to go down on Oct.15, its me who will pay 1month salary to my employer. Is it right?..please have some advice.. B