What can I do if I was divorced years ago, the house still in my name and my ex never refinanced?

From your description it seems that the title may be in his name. But, most likely the debt is still in your name because he has not or could not refinance. You might talk to your divorce attorney to see if there is anything you can do.

Whether or not your ex refinances is not important. In California, there are a set of statutes in the Civil Code called the Fair Credit Reporting Act. The sections you are interested begin at section 1785.10. These set out a detailed procedure for contacting the credit reporting agencies (Transunion, Experion, and Equifax) and demanding that they correct the information they are reporting about the mortgage. There are several good books available that will walk you through the process. There are also people who specialize in repairing credit. You do not need an attorney for this. The credit repair expert I have used charges $150 for each item you want corrected. It's a small price to pay to save all the hassle of doing it yourself.