Vauxhall Adam Rocks 2016

Are the actual headlamps discoloured at all? The plastic lenses on cars can become discoloured with dirt and heat of the bulbs.

Halogen bulbs do go yellow and lose brightness over time,

I've had success with the osram night breaker bulbs in my Almera.

As for led options you will have can-bus on that model so you would need to make sure the bulbs you buy are suitable otherwise the car will spaz out and tell you your bulbs are out. Generally the decent brands, osram have the can-bus bits built in the led bulbs. Led upgrades are very expensive mind, the osram are like £60 for the pair