One Time Charges and Credits

I just received a $57 charge without explanation. it's just listed on the bill as "One time charges and credits." what kind of a company makes a charge without even a hint of explanation? recent bills had been consistent and what they are supposed to be. then they want you to take time off work to call during business hours, without an easy to find way to email. Cox is basically a monopoly where I live and clearly they take advantage of it. I changed from automatic bill pay a few months ago to avoid surprise payments, and now at least I have a chance to check it before paying. so annoying!