My e class 2016 has xenon bulbs, I'm told they are pretty expensive but last a long time. Had a quick search and the best deal I could see was £53 fitted from a well known outfit. (one bulb)
Fragile too when being handled/
Let the "outfit fit them"
Also, I believe, high voltages that need to be discharged before doing anything else.
I don't want to change them, I was curious to see how much they cost.
Whatever you do never investigate the replacement cost of LED headlights.