How can i fix my clio central locking and electrics?

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. Today after going on a short drive i locked the car using the key fob but could not unlock the car. the fob did not respond even though the red light flashed while pressing it. I had to go in through the passenger door using the manual key as my clio driver side does not have a key hole. this set off the alarm and i could only get rid of the alarm when i managed to start up the engine. Does anyone know what is wrong and how much it will cost to get fixed. The car drives absolutely fine.