I switched my family cell phone account to T-Mobile at their DuPont Circle store on July 11, 2012. The salesman impart incorrect information on quite a few counts the two most critical being: International calling over WIFI to a land-line is free, and they would not charge us to port our existing number on a different carrier in after account setup.
During the purchase, my wife asked specific questions about the wifi calling feature as she frequently uses Skype and Google to talk to family overseas. He reiterated that she could now do this over wifi without using those services at no additional charge as long as she called a land based line.
I received my first bill on the 20th of July after 9 days of service. It was for a total of $575.94! The bill included $246 in international calling charges. I spent several hours on the phone in attempts to resolve this problem to no avail. I returned to the store to have the salesman resolve it only to be informed that he is no longer there. I called customer service again and finally got a rep who agreed to reverse the international charges. However because of the poor experience I decided that day to return to my prior carrier. I did so on 22July.
All told, we were on T-Mobile for 11 days. They are refusing to prorate our final bill even though we left during their 14 day window of being able to change your mind, and instead are billing for a full month of service for the two days we were with them after our first bill was sent. During the short time with their service I was subject to recalcitrance, incompetence, and callous indifference. All of their personnel, save one, made promises that the later rescinded, or failed to follow through on. All in all a poor way to do business.