how much would it cost to fix the central locking in a 98 clio? ?

I currently own a 98 Renault clio grande rn. The remote sensor for the central locking of the car with the key fob was removed before i bought the car. The car locks from both sides but i have to press the central locking button on the inside of the car before i get out so that it locks all doors at once. When i wish to open the door i must open at the passengers side because the drivers locks but dosent open and press the central locking button again. Is there any way i could fix the central locking so that it opens all doors at once with just the key? and how much would it cost? thanks a lot

kyle