Ambit Energy Charged extra money for April, won't give it back. Plano Texas

In April, Ambit Energy charged me $200 for electricity. Then they charged an additional $320.58 as an additional charge. I had trouble getting through on the phone as they say I wasn't a customer even though I was and had been using their services since 2013. My wife was able to get through and they refused to give a reason for that extra $320.58 and they would not refund it since I had automatic billing. I am very angry. My wife signed up with them without my knowledge because one of her friends was a consultant back in 2013. This company is a scam as they don't provide electricity. Never use this company. It's nothing more than a MLM scam that robs customers blind.