Welcome MMXBenz,
I just got a an '09 Black C300 and the previous owner didn't really care too much about swirl marks.
I started out with a PC XP 7424 a couple of weeks ago. I also purchased the Menzerna Power Gloss, SIP & Super Finish. I worked on the car 2 days trying different combinations. I did get some of the swirls out but they are still quite bad. It actually led me to getting a Rotary (Flex 3403) & ordering the Flex 3401.
Right now I'm experimenting on a junk door from a black Mercedes waiting for the pads for my 3401's pads to get here. Hopefully today.
AG recommended the Menzerna line along with the CCS pages. Orange, white and gray or red along with a Yellow and the power gloss for any tough areas.
I'm happy with the Menzerna (course I don't have any experience with anything else.) but right now I just got the Meg's Ultimate Compound, #105 & #205 I'm experimenting with now. Mainly because it's about half the cost to play with. So far I'm liking it just as good.
Oh yeah, I had some store credits so I ordered a Foam Cannon for my pressure washer in hopes that will help with the swirls!!
Keep us posted on your results.