Walmart Family Mobile T-Mobile I paid the bill after talking to the company, Now they say I owe .25. They charge 3 dollars to pay it Nationwide

I bought a phone on my way to Vegas. I had it for one week. I turned it off after a week. I never got a bill until it said I was late. I contacted the company verified the amount was the same as what was on paperwork (bill).  When close the account they cannot give you the money you. You have to wait to get the bill. You cannot pay it online because it is a closed account. The is no place to mail the payment. Soyou can go to walmart and pay but they charge you. You can pay it on the phone but they charge 5 dollars. I make the payment at walmart now they say I owe them .25 but I would have to pay 3.25. this is not a way to run a business. walmart or t-mobile  needs to be accountable