Consumer Cellular review: Mysterious 2nd line

I was charged for a 2nd line that I didn't know existed on my bill. I did not see it because I set up auto pay and just received a dollar amount every month that never fluctuated wildly. Upon asking to receive a refund for the unused 2nd line added for... some reason, they refused.
They told me I should have checked my bills every month. While this is true, it is also true that the line was added without my knowledge or consent. This may have been due to a technical glitch or clerical error. Either/or, this is no way for a business to respond to this type of mistake.