Green Mountain Energy I've paid over $3,500 in electric bills over the past 5 months, Internet

I'm a single male living in a single family home and I travel a lot and over the course of the past six month I've paid over $3500. This doesn't include the six months prior to the six months I've just listed. Green Mountain Energy is one of the biggest rip off/Scams that are allowed to do business in this country. My rate per Kilowatt jumps around like nothing I've ever seen. When I told the sales associate I was discontinuing my service because of such high rates she then offered to drop it to 12 cents from 21 cents. My question is why was it 21 cents to start off with? I would  like to seek legal advise on suing this company and making them a public spectacle  on how companies like this take advantage of struggling americans. I've seen numerous complaints about price gouging with Green Mountain and it has only been recently that I'm able to switch electric companies because of having to put a Hefty deposit thanks again to GME. If there are any lawyers who would be interested in this case I would be very interested in hearing what my options are for bringing this company to justice.