Lived and earned income in both CA and NC states during the year, CA asks for additional tax payment on NC income, what should I do?

Dear experts, I really need help here on what to do for my situation, this is for my personal return filed through Turbotax back in 2015 tax year (sorry about the long post):

 

  • I worked in two different states in 2015, received two separate W2's at the end of the year, one for my earnings while I lived in North Carolina (Jan to May), the other one was for my earnings while I lived in California (Jun to Dec). However, both W2s have my California address on, since I moved to California mid-year 2015, both W2's are mailed to my California address.
  • I only filed the CA income W2 (June to December) with CA, not both W2s, because of the other W2 associated with my earnings while I was physically living in NC (January to May).
  • CA Tax Franchise Board discovered the NC W2 and asked me to pay CA state income tax for my income earned in NC, because I have a CA address on it (which might caused them to mistakenly think I physically lived in CA for the whole year). 
  • I talked to a specialist from CA tax agency on the phone a few months ago regarding this incident, and I was told to go back to my prior employer to re-issue my 2015 NC W2 with my NC address on it.
  • I contacted my prior company's payroll and HR department, however, they told me they couldn't update my address on the 2015 W2, I should just file the NC W2 to NC regardless what's my address on it, don't file to CA, which was what I did.

CA is still asking for payment, and since NC state tax has already been withheld in my NC W2, paying CA again would result in paying double taxes on my NC income... what should I do here?

 

Thank you!