Complaint Review: t-mobile

i had closed the account with t-mobile aug 7th and made last payment on sept 2nd for 57.00 and later i received new bill saying i owe them 56.76  in november yet i already closed the account and transfered phone number to sprint and they still charges me for the month of august after the 7th for non existent service i did verify no service on sidekick lx and my new htc evo 4g using that transfered phone number under sprint so i call them 4 time to striaghten out the billing mistake and they told me they would take care of it then later mades several harassing calls to get me to pay it and i refused to pay them for service that doesnt exist and 6 month later i get harrassing calls from collection aency slaming me for 56.76 it was bay area credit service lcc which doesnt exist their website get looping back to home page after clicking on pay bill hmmm... it did happen to me and my friend's too so i think they trying to pull last cent practice