How should I deal with problem car dealer?

We picked up a 2007 CLS320 with 115k on the clock a month ago, after a promise of 'if there's anything wrong with it we'll fix it' BS from the salesman in a big 300+ German car specialist (who shall remain nameless for the moment) we drove away happy.

I'll try and keep the history brief.

Pretty soon it was obvious that a rattle from the rear and a broken CD multichanger that they knew needed fixing had not been repaired.

So they had it back for a week and repaired a broken spring and fitted a nice Denison gateway instead of fixing the CD changer, as well as other things I had identified.

But all was not well, the car rattled all over the road over the bumps. So, no messing about, a half hours labour at MB and i get a report that says front ball joint and rear barrel joint has exessive play.

I was told they've changed both front ball joints and one arm on the front and one on the rear and both rear spring. I've picked it up today and there's still a rattle at the front!

The springs are done but they've only done one ball joint and the rear bottom arm (only the part MB recommended.

I've done over 350 miles taking it back and I've had enough:mad:

There's so any ways I can deal with this.

At he moment I just feel like blowing the whistle.