T mobile won’t give me my refund

They over charged me for three months and instead of giving me my refund they lied and said I knew about the change in updated information. When I didn’t. I also can’t sue cuz the money they took wasn’t big enough for a lawsuit and all I can do is send a complaint that will never be compensated.

Since I can’t hurt them like a wound I wanna bother like an itch they can’t scratch. Enough to tickle them but can’t sneeze.

Anyone got bright ideas?