First check if it will work on your spare key . Try to check if batteries are stil good.
Second,Check if central locking electronic control unit is working/ receiving signal from you key transponder. This is located behind the right hand footwell side/trim panel. Check any loose wirings.
If box is busted, will cost you a hundred ++ quid for that + programming + vat.
My remote can only open the door..but have to close it manually.
You may try synchronizing it, by turning the key on the ignition without startin it and press the open button for 3 secs.. If it clicks and the door locks open. No need to go the dealer /garage.