clio rxe 1998 alarm problem?

hi,
since i have had the clio my key fob has never worked so i lock/unlock the door and central lock inside from the button just above the gear stick..
the immobiliser still work and can start the car but as soon as you open a door or try to start the car the alarm goes off!!
i cant drive with the alarm going off obviously so anyone any ideas ..
ive tried to dissconnect the battery but wen i connected it again same problrm alarm just sounds constantly untill u lock it again
id be grateful for any ideas
thanks
amiee