TMobile Financial Services, Billing They charge credit cards, but don't give credit to account Internet

My former phone and Internet Service provided, Tmobile, had overcharged me. Back in July of last year, they had contacted me, said a payment was missed nothing showing for March of last year.  I went to the store, I purchased my phone and airtime card out, with copies of my Visa Statement, store says, Oh we really Don't do that here anymore.  I fax a copy of my Visa Statement, after speaking to their Finance Department, showing monies that they cashed through my credit card, faxed to their - get this - LOST MONIES department.
See when they didnt credit me my March's payment, they had also, double charged my account for July for it, and they overbilled on the payment itself.  I sent my complaint to the FCC, Washington, D.C., mailed it in back in December 2011, to date, no answer, I sent them their form, copies of my visa statement, I refused to pay what would total 14 payments in a year, because no credit, showing they cashed, were credited to my account, NOW, Tmobile has sent this to Finance, now I stopped using their products since early January, I was on a month-to-month, did you know, they continued charging
me to this day, like I was a current customer and EVEN reported to a collection company twice the amount on the account they have now taking 161.83 owed me yet currently trying to bill, for no services used 350.00 currently?   They also,
do not protect you from Hackers, I had to do it on my own, Tmobile said Impossible, can't happen, as people from all over called me, for a guy using my number, etc.  They can save me the cost of the filing fee for court, how can any company,
take monies off your credit card, cash it, it gets posted on your card statement, and not credit account?  Went to New provider beginning of month, wonder if anyone else went through this also?  PS Store said go to another store over it, they gave me an address of a Tmobile store, that was vacant, had a for lease sign on it, empty.  CROOKS.