problem with california rn license endorsement

I applied for California RN license by endorsement and received a letter from CABON recommending additional coursework due to concurrent issues (mine has to do with Med-Surg and Obstetrics). I don't see the point of going back to school becuase I have been licensed in Vermont since 2007, had it endorsed to Texas BON in 2009 and worked for 2 years as full-time ICU staff RN in Texas. Aside from a BSN degree in the Philippines, I also hold an MN degree. I have written CABON twice by mail and email, no reply. Called several times but failed to speak to anyone. How is this possible? Any advice? Thanks.