I watch still being charged

I have been paying automatically and slowly my phone bill has gone up. Checked my bill and they have been charging me for extra line for 3 years at $15 a month. Granted I should have checked but I didn’t. Doesn’t really matter cause a company should not be allowed to do this. So I talked to customer service and they said they could give me a refund for 3 months only cause it’s my fault? Really can you really do this. I ask for more help from someone higher and I get emails and phone #s that don’t work. I need to speak with a supervisor who can correct this and refund my monies 

Re: I watch still being charged
Customer Service Rep

Bokay2, thanks for reaching out. I understand having a charge on your account for the past 3 years can be a bit of a concern. When you spoke to Customer Service, were you able to get that line removed from your account to avoid future billing?