the factory wheels are cracking on my 2013 c300 sport

There is a problem with the Mercedes rims. They are cracking to easy. My front driver side tire kept loosing air pressure. I took it to Goodyear and they said that my rim has a crack in it. I did some research on the internet and realized that this is a common problem. I called the dealership and the said a new rim would be $500.00 core price if I turn in my old one. I will not purchase another Mercedes until they own up to this defect.