Did Sprint break any laws in this situation?

This started back in October last year. A representative from Sprint called me and was upselling me a tablet. No disrespect to the representative, but her English was terrible. To make a long story short, when I got the bill a month later, I was charged far more than I was expecting even though I made sure I asked what it was going to cost. Anyways, I refused to pay my bill and closed the account. The account was sent to collections in January according to CreditKarma. Today, I look at my bank account and Sprint took $684 and sent my account into the negative. Essentially, I have been charged twice. Once by Sprint and once by the collections agency. I dont even know how Sprint took the money out, because I cant overdraftvmy account.