black handles and roof bars

[Wild1]

I have recently purchased a C Class estate 2001 model and must say other than a few small issues that the guys on this forum are slowly helping me sort out I am super happy with the car. However the previous owner was not so careful during polishing hence I have a number of white stains on the door handles and roof rails.
What is the best way to make these black again?
I have seen many products out there but then after reading many posts I also see that many say none of the products work. I was wondering if there is any advice from you guys as to what you use for plastic and rubber?