In your case I would bring it back to the store, they can repair this for you. Or at least send it back to Pioneer Service for you. Just claim warranty so they research it for free and let you know if there are any cost. If so they should be pretty low as this is not an expensive repair. At least, this is the way this is dealed by in Netherlands. I am NOT aware of the exact policies in UK so you should check at your store.
This is a repair you could do yourself if you have experiences in soldering electronics. If this would be your first tryDON'T EVEN THINK ABOUT IT !
If you check out my topic about the CDJ's LED modification
you'll see an image of the circuit board that hold the LED's but also the switches.
The section for the CUE buttons is simula to that of the PLAY button. In this image I've marked the location where the LED's are mounted.
At the bottom of the circle you'll see the notification 'S1302'. This is the PLAY swtich and need to be replaced by a new one.