I applaud your efforts but one thing in the letter catches my attention and will probably catch theirs:
" it is state law that allows me to carry a firearm either openly or concealed, so untill you comply with that state law, " should be different. Laws tell us what we can't do. There isn't a law that say's they have to let us carry in their establishment.
Now because of their policy, I haven't stepped foot in that mall in a couple years now and I won't until it is changed. There are way too many hoodlums in Winston and they like to hang out at that mall and Four Seasons. I go to neither. Good luck with your attempts.