I try to avoid MB dealerships as much as I can. This type of situations are the ones are not, sadly, "unfamiliar" to MB dealerships (with a few exceptions) but you will rarely find in an independent garage. People in this forum have different experiencies and opinions on MB dealerships but, most people would steer you away from them after the warranty is over but, that is another story.
Going back to your problem(s), do a search on the "gurgling noise" on the right upper corner on this screen. I know it was discussed before but, I do not know if it applies to your car. As far as being "noiser": is it the fan noisier, the air, etc? It could be that they cleaned or lubed the blower fan and now it is rotating better. Who knows?
Bottom line is: you paid for it and they have to fix it right.
BTW, how can the service manager been good if you still have the problems and you have no confidence in this shop?? Remember who he works for....