I wonder if your main car battery isn't now charging enough to be able to unlock the doors then? Have you had a new battery recently? Have you had your alternator checked? (This charges the battery)
I know it might sound a bit daft, but try locking and unlocking your car doors a few times while the engine is switched on and the key is in the ignition - see if that helps.
It did with mine. If not, there's a small chance your key's may need re-programming.
Personally, after trying the key thing, I would nip it into your garage and ask their opinion (they probably won't charge you for a quick nosy or their brains picking)
If you're worried they'll charge you, you could always call Renault servicing and pick their brains instead.