I am sorry you have had to deal with this as it should be a fairly simple fix. I would recommend that you call our Team of Experts folks over the phone so we can ensure your name is updated in the billing system.
Just some additional information. When your phone calls someone else, T-Mobile does not transmit your name, only your phone number. At the receiving end, your phone number is matched to a database of names so that your name can be presented. The problem is that there are actually several different database lookup services, each independent of the others. All T-Mobile can do is to send your information to all the services and hope they all update their databases. If one does not, all T-Mobile can do is try again.
Does the problem occur when you call another T-Mobile phone?