A key question

[bobmcc13]

My recently acquired 2 came with two keys.

One was the courtesy key, the other a black one with two buttons.

When you press the 'Unlock' button the button clicks and the LED lights and the car reacts.

When you press the 'Lock' button the button doesn't click, there is no LED and the car doesn't react.

Do I need a complete new key or can I just buy the fob with the buttons and transfer the blade and innards to the new fob?

Or is it going to be a complete new key?

Bob McC.