Q: Do you have to be a T-Mobile customer to do this unlock?
A: Yes. T-Mobile's contract states that it will only do the unlock for you if you are a member with them for 3 months, and are in good standing. This is to prevent losing customers.
Q: Do you need to be the account holder?
A: No. You need the last 4 digits to the account holders social security number (a standard T-Mobile customer support feature), and then you have provision to unlock the phone yourself. This is, mainly, to prevent theft.
Q: This is taking to long!
A: T-Mobile will normally take a MAXIMUM of up to 2 weeks to return the unlock code. I've heard reports of instant over-the-phone unlocks, and have heard the worse scenario being 2 weeks (as mentioned).
Q: Why not just buy one online?
A: Why would you buy something, when you can easily do it for free? Stop being lazy!
Q: I am not a T-Mobile customer!
A: You can either find a friend who uses T-Mobile, or call up HTC and have them unlock it for you. I've read around and calling the factory is a bit more of a hassle, but it is legally possible. I have not tried this yet, but I can assure you, from prior experience, this works fine with Samsung devices