Refurbished Bathtubs How Can I Clean The Refurbished Bathtub?

How can I clean the refurbished bathtub? - refurbished bathtubs

I had renovated my bathroom. They told me to clean the bathroom with 409 or Fantastic. I spray the tub with 409 and wait and then spong cleaning. But the black things do not disappear. It is dirt. Once I had the company that refurbished guy called and came to be cleaned. I can not tell the company to clean my bathtub. told me not to use products which do not wash the car. Someone with whom I have to clean the bathroom with white vinegar? Please help.