This is very frustrating to me as well. I have been a T-Mobile customer for 5 years and due to living over 100 miles from the nearest retail location and not having a day off during the open enrollment, I was unable to enroll in Jump either. Since I just entered an EIP for an iPhone back in April, I am essentially out of luck until I pay off this phone. As I have no other family members to get a phone for, telling me to add a line if I wanted it as happened when I called CS was a smack in the face.
at the moment, for the first time in 5 years, I am quite unhappy with T-Mobile. This is not a good way to treat a loyal customer.