i have been in customer care for just 3 months. i have never given the 6th month free or been told that i can or even seen it in the system TO give it. i've only seen it already on accounts. so that leads me to beleive it's no longer given out.
if you change your mobile number, you MAY lose grandfathered plans. when they tell you that, ask them to speak to a lead & see if they'll let you keep it. i don't know what specific plan you have off the top of my head so i'm not sure if you can... but probably.
bonus minutes are basically at the discretion of the person offering them to you.
i hope its obvious that my views do not express the views of t-mobile. anything i say should be viewed as my own opinion & no reflection on the company i work for.
"It's like a new pair of underwear. At first, it's constrictive. But after awhile it becomes a part of you." -Garth Algar