Thanks for all your advice!
I'll be sure to get my bf to look into all of those possibilities.
He knows this car inside and out, however; some of the problems that occur are just strange and plain weird (a lot thanks to CISE).

Unfortunately Hirnbeiss, he has to fix it, the guys at our local Benz dealers (he worked as an apprentice) have very little knowledge on our car and we don't trust other pop in mechanics. I'm sure with everyone's help he'll be able to figure it out.

Again, thank you for your help.
Keep the advice coming and I'll keep you posted