To get rid of the condensation, you'd probably need to get the headlights off the car (take the bumper off), and apply heat (I'd suggest a hairdryer) into the headlight from the back cover- Do this until its clear - probs 30 mins
then put the cover back on, and ensure it is sealed up properly - may need to buy new back covers - £14 each from dealer.
If there's any cracks in the headlight - this will need to be sealed up too - kitchen sealant maybe..
i just popped a couple of large bags of silica gel in mine for a month or so... took them out when the headlight was dry then reversed the gasket on the cover, put a layer of grease over it then refitted.. been dry as a bone since
I tried al the suggestions including silica bags but non worked so after I had taken the bumper off which is a simple job, just search on youtube for a vid, I took the unit out and found that the seal had failed around the bottom edge where the lens meets the body so sealed up with some silicone and let it dry out overnight. Not had a problem since.
If you use the silica bags either tape them in place or what I done was tie some string around them and trap the string
in place with the covers on the rear of the headlight, it will stop the bags moving around inside the headlight and getting
damaged or damaging something inside the headlight