I got a quote to service my Mercedes A150 and it came up to about £250!! :-O
So I asked the lady what if I bring my own oil for the oil change??
£70 off!!!!!!!!!!!! :-D
So i went to Halfords and bought 5L of oil for £20 and gave it to Mercedes when my car went in!!!
And saved £50!!!!
This was done over the phone to Mercedes Leicester, but I'm pretty sure other Mercedes dealerships will do this for you!
Can't go wrong!! Hope this helps! :-)