T Mobile Company charges you for their mistakes...Beware Fayetteville North Carolina

I go to T Mobile on Raefor Rd to start a service on a old T Mobile phone I found in my closet. New number and sim card, should be simple. They port my active number from my iphone to this phone.  I see the paperwork and asked what have you done...I come in for a new service and they ported my phone from ATT, then say there is nothing they can do...I havbe to go to ATT.  I go to ATT they say they cant see where the number is being ported I should be ok.  That night at midnight, my iphone shows no service. Later that morning the t-mobile phone rings...it's my number and I have to take the call.  I go to ATT when they open at noon and finally get my number ported back to my iphone. I call T Mobile that evening (1 Apr) I wish I had written down the name of who I was talking to. He documented my complaint, closed my account, put me on hold to clear up billing and was extremely apologetic. He advised t was taken care of.  On 12 April what do I find in my mailbox? A bill from T-Mobile, dated 2 Apr. Of course I get on the phone again this time I talked to Anne first, push the wrong number for the issue and was transfered to Amber. The note was written by who ever spoke to on the first, but Amber tells me I am responsible for the charges on the bill...I used the device. DUH like I had a choice because the people at T-Mobile screwed up. I asked to talk to a supervisor...Amber was right I got the same response from Denise but she said it could have been fixed. Not by the people at the T-Mobile Store...they sent me to ATT...I am tired of excuses. T-Mobile needs to take responsibility for their stores, their employees and supervisors and not blame the consumer when they screw up!