For all those having issues with removing dried wax from any exterior plastic on one's car, use 'Magic Rub' erasers. They definitely work and not much effort is involved. Tried many solutions and all the wax (dried) has returned. Some may know of this but posting anyway.
One must have these 'erasers' in their detail kit, always. Guaranteed to work, and work efficiently. I learned of this last year, after trying every possible way to remove dried wax from black plastic.