Infantry dug in? Direct fire from the machine guns or even the tank turrets unable to dig them out? Perhaps your command needs to add a Heavy Mortar or two to the inventory.
Lobbing a massive 250mm mortar shell almost vertically into the sky does result in a significantly shorter range than conventional artillery however the ability to hit behind buildings, down gullies and through the top of bunkers or tanks far outways the shortfalls - pun intended.
Your heavy weapons team may complain about the effort required to lug the 250mm shells up into the breach but they always smile when the first round lands down range.