Renault Clio electrical fault

I have a Renault Clio Expression 2003 and sometimes while driving the red light on the central locking switch turns off,, when this happens i cannot use the central locking switch, hazard lights and indicators, electric windows and wipers. However the headlights and CD player still work. Also once when this happened after i turned the engine off and tried locking the car, the key fob did not respond. I could see the red light on the key fob when i pressed the button but the car did not lock. After this when i tried to turn on the engine, the ignition came on but the engine did not start. After trying and waiting for a few minutes it went back to normal and started up. Sometimes i cannont get into the car as the key fob does not respond. I end up going through the passenger door using the manual key whoch sets off the alarm. Finally after starting up the engine the alarm goes off. Does anyone know what is wrong and how much it will cost to get fixed. The car drives absolutely fine.