Probably the only fix is to paint it. A good polish with a UV inhibitor may have prevented the issue but it is too late now on what has been damaged. I would still recommend doing so on the rest of the coach to prevent further damage to other areas. Good luck and keep us posted.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7