my immobiliser on my clio s plate is playing up?

i have an s regestration clio 1.4 rt and it was broken into and the immobiliser went and stuck on and the fob key was damaged so i payed renault 130 to have a new key sent and recoded to my car and it worked until i stopped and started the car for the 3rd time and it locked on again so i was told to get a new ignition ring which i did and it still doesnt work so renault have told me i need a whole new unit but i was wondering if maybe the battery just needs charged because the car was sitting idle for a few weeks before i bought it and it went dead not long after i got it through me trying all the time to start it with this immobiliser problem is this possible