Sprint review: a sales agent at walmart

I went into Walmart February, 1 to get a phone less than 100 because I was on a budget. The agent there was wearing all black. He told me that I could buy a phone for a special. The special was 5 dollars and some change a month for what he told me was 12 months. He told me the total for the phone would be no more than 25 dollars and change. I gave the person there my debit card, social security number and all my information. He charged me 50 something dollars. He then printed out my contract with the billing and the price for the phone. The price in the contract was more than what we discussed. I told him I wanted the correct contract and paper form of the price I was paying. I called sprint customer service, to get answers and still don't have a answer. I returned the phone and all the items same day. I called customer service to get answers on the bill and why I was being charged. I never got a answer and was told I still have a bill due my name is Jasmine Michel phone number [protected]