vauxhall vectra key fob/alarm?

hi the to keys for my vectra dont work.. ive opened them both and found that both battery holders have compleatly come away from the chip board in both keys.. i can still open the car by putting the key in the drivers side door witch opens the central locking all round and i can still start the car but every time i open the locked car with the key and open the door the alarm goes mental untill i put the key in the ignition and turn the car on. this is really doin my head in and i need help.... please can you help me....