Use a proper Tar removal product such as Autosmart Tardis.
AG Tar remover is not very good. Spray on and leave for a couple of minutes and then wipe off with a microfibre and rinse.
It will remove all of your wax so you will want to re-wax the area,you might as well iron-x and clay and then wax/seal after using Tardis to reprotect the area.