Is the the account you're transferring a T-Mobile account or one from another carrier? You'll need to be the primary account hold to make a change like that. Please let us know if you need more help with this.
Let me try and fully understand your question.
Are you saying you and your ex husband have since seperated/divorced ?
And your name is on the account but your last name on the T-Mobile account is of your marriage name?
If you are the Primary account holder, and if what i stated is true above.... you can visit a T-Mobile store with your ID and maybe even a marriage certificate to prove that you are indeed the account holder but your drivers license has your marriage name on it. You may even be able to contact T-Force (T-Mobile's Technical Reps) on Twitter and/or Facebook and tell them your dilemma... they should be able to assist you and let you know specifically what documents you need to authenticate your Identification which will allow you to take advantage of the BOGO deals from T-Mobile.
But if the account is under your ex-husband's name.... he would have to initiate the BOGO deal because it's under his name. Not sure how things work due to Divorces paired with cellular plans.... If a judge can order him to allow you to take advantage of the BOGO deal.... that matter would be best answered by a divorce lawyer.
I really hope i understood your question and answered it to get you headed in the right direction .
Did you still need some help getting your BOGO offer? Please give us a reply and let us know how things are going.
Just wanted to check in!