there is currently a plan for the 55 and up crowd that includes two lines for $70 total which includes taxes and fees for unlimited LTE data however there are some other limitations that are not the same as the T-Mobile one plan.
I am on a Pay As You Go $3 a month. I LOVE it! Free 30 minutes a month. When used up it is 10 cents a minute. That inludes texts and messages. I don't do texts and messages.
Manage your T-Mobile account