Hello, I have had a similar problem, my key fob would not deactivate the alarm or the immobiliser, renault wanted a stupid amount of money to look at it and they wanted the car too, I eventually found a local independant renault specialist, I took the key to him and it turned out to be the souldering in the key, the infra red bit had become detached from the circuit board so although it was sending a signal it wasn't the right signal. He resouldered it and it works fine now.
There is also a code available to override the immobiliser, (depending on the age of your car) renault will tell this code does not exist and it is not possible and even if it was you would damage the ecu, this is all rubbish. (I have got the code for my car from the independant renault specialist!) I am currently trying to confirm whether it is actually a legal requirement for renault to provide you with this information. It does seem to be a UK issue!! I hope that helps!
Karen
November 2007
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix car alarm systems.