He's spamming penels into T34-76, you got only 3 grens out, besides dumping 60 ammo into each squad for that artificial 5th team member that can be dropped and can't fire on the move you also have elsewhere to dump ammo, Panzershreck for the Panzergrenadiers for example, mine sweepers, etc...
What do?
Edit: I still haven't seen proof of what you've previously said tho, looks like you're hiding from my comments until the opportune moment for you to reply to me.
If someone is spamming penal, the best answer isn't grenadiers even with Lmg upgrade, Penal are Anti inf units. A 5th man isn't going to solve anything.
I'm not sure if a Penal spam into T34-76 works that well.