Cox is Robbing Me Blind

So last October (4 months ago) I ordered both basic cable and internet service from Cox. Between the 2, my bill was roughly a few dollars over $150 a month. Quickly it became apparent that we really didn't need the cable service so I canceled it and just kept the internet service. The bill was now $80 a month which is fine. Then January's bill came in, $173 - huh? Wtf? How... called about it and they said because I was charged for the cable box I didn't return - which I did, btw. No matter how much I stressed that the box was returned, I still got stuck paying it in order to prevent the internet from being disconnected. For January I paid $150 and carried the remaining $23 over to February. Paid $100 for February - this should've brought my balance back down to $0, but nooo... three days later my internet was shut off due to a $53 balance left on the account. Because my son needs the internet for school I paid it to get the service back on. Again.... their glorious app said my balance is $0. Now here we are, the end of February and I got cox automated calling me on the daily citing I have a past due balance of $170-some more dollars due immediately. How the hell???!