Overcharged

I transferred to Tmobile from Verizon. I was promised $ 130 per month. Been getting charged $ 196 for months. Been back and forth with NYC store rep who keeps promising it will be resolved but still getting overcharged. I only received a few credits towards the $ 196 so far. Now store rep wont answer text or calls. I stopped in the store 2 weeks ago and again he promised resolution but nothing.