AT&T Mobility Cut my service of possible fraud , $346.81 reverse and bill balance issue Atlanta Georgia

 Hi there i need help , iam Luis Zxxx Sxxx and iam 63 years old disable men also iam, new custermer in att and i have i gree a 2 year contract that i was approved in the store where they verify  my credit check and they approved my lines for free and i got the proof of my Purchase ,and in only have been less the a month of service here come my issue and complaint this people in att cut my service on April 2,2013 because of some posible fraud in my account. well they told me to fax o send my state id and a light bill to confirm my address and that a iam the owner in the account

so, the next day a fax my state  id the light bill and i resend the fax about 15 times till they got it and approved that iam Luis Zxxxx and put my service back so iwas 2 days with no service  and never explain me what happend ,also the same day the conect my service back, i was talking to an agent on att custermer service and he credit me $346.81 and my balance was on zero on may2,2013 and i received a text from att saying that i was credit and my balance is on 0.00, here we go may 3, 2013  so that night they gave a credit after they shut my account and service and balance was on 0.00

when i woke up in the morning on may 3,2013 and when to my computer and log in to my account in att my balance is $791.81 and they also took away the credit they gave me that night but i got evidence of the credit thet gave me that balance was  on 0.00 and i calld and when tru alot of hours and they saying that the 791.81 is an error because when they cuy my service of some lame fraud because i prooved them that there was no fraud. so the mistake was the where charging me with the cancellation fee , so now they want to charge me with 346.81 the  same amount of the credit thay gave that balance was in zero and know they took away from me and charging me with 346.81 after all i wentru as a new custermer and want to ripp off my money no please investigate and take legal action please.
Product_Or_Service: Apple /IPHONE 4 8GB WHITE/Famaly Talk Nation 700 With Rollover
Account_Number: 787-710-4513