family mobile-walmart 1st monthly billing brighton Nationwide

Well my first problem started with the amount I was paying. I was suppose to pay around 30 a month so I called they said it was the tax so I dropped it but then when I changed carriers they continued to charge me and sending letters saying I owed. at 1st I thought it was a mistake so I paid no attention to them till I got another bill for a higher amount. I was already using another service with same number u would think they would get the hint being somewhat a prepaid company. But no I called n they said they would send me to collections and I had to contact credit request@family mobile. com and never got response.  All I want is for the charges to get dropped. It makes no sense.