reimbursement problems

I want to express my extreme disappointment with T-Mobile. I used to have AT&T and never had any problems. Since I moved to T-Mobile, in just one month, I have had three significant issues.

    1.    Main Problem: I paid off $397.11 at AT&T to move to T-Mobile, and more than 30 days later, I have not received my reimbursement yet. I completed everything with the attendant at the Prosper, TX store, and even so, they have not sent me the reimbursement. I called the call center, and they told me I needed to send the bill showing the payoff. Obviously, I do not have access to that bill anymore since I am no longer an AT&T customer. However, I have my receipt from AT&T showing what and when I paid off, and I sent it to them today, August 6th, by email. It is clear that T-Mobile's process is a total mess because they are asking me again for something that has already been sent.
    2.   Internet Issues: The internet performance is poor. In Irving, Frisco, and the surrounding regions, the device is unreliable. You can't use the high-speed service. I really do not understand why they continue to advertise this kind of service.
    3.    Service Abroad: The service abroad is even worse. The partners that should provide service in Latin America seem to be the cheapest ones with the worst coverage.

My question is, what kind of company is this?

    •    Poor customer process
    •    Poor customer service
    •    Poor service both inside and outside the country

I want my reimbursement and am considering returning to AT&T.