How do I get in touch with corporate (or at least someone who has some authority)?

I have been a loyal Verizon customer for 10 years. I had an iPhone 4s that was completely at the end of its life so I chose to upgrade. After going back and forth with Verizon I was left with either upgrading my phone at FULL price or not being able to keep my unlimited data plan that I had for many years. After much discussion and promises that I would never use 6GB of data I chose a plan with 6GB of data because this would keep me as close to what I was paying prior to the plan change. Here we are three months later and each month I either go over the 6GB or have to stop using my phone so I don't go over. Tonight, I contact Verizon customer service and was told that there is nothing they can do. In fact, when I suggested that I shop cell phone carriers the rep told me I should and that he thought the customer service at Verizon stunk. What? How do you work for a company and tell me I should go elsewhere. I asked if the call was recorded and he said yes. He then proceeded to tell me he thought corporate was basically out for themselves and could care less about the little people. As a long time customer (who always pays their bills on time) cannot believe that Verizon cannot do anything regarding this. Not to mention that they employ individuals who tells current customers to go elsewhere.

Please help!@