Hi i have a 2013 fabia monte carlo with the passenger side headlight misting up. is this common as dealer has brushed it off.

Welcome.

Don't think it's common; and not on a 2013 car.

Early Fabia's (as in Mk1's) had issues with headlights going cloudy through UV degradation, of large, etc. but not misting.

I'd go back.

Hi from a fellow South Waleian,

Where about are you from?

I echo what is said above, not normal and certainly not acceptable on a 2013 car.

I'd be back to the dealership if it were me.

Neil