Solution imo: Decrease range on both the elefant and the ISU to like 75. Give the ISU a higher scatter ratio so it has a higher chance of missing gren squads. Reduce the dmg output of an elefant so that it's equivalent to a tiger, but give it an option to lock down(like the Marder in VCoH) where it is able to deal the dmg it has done before, but be forced into place. (Takes lets say 8 seconds for it to move out of place once it's put into place at w/e time you decide you want to move it). This allows for both units to still be effective, but with limitations. Arty, multiple tanks, etc... will be able to counter it effectively if unsupported/unwatched.
This would be great solution and exactly similar thoughts as me and my mate were thinking yesterday.
However I doubt that they will make this radical decisions.