Wow that's pretty reasonable rate IMHO as their prepaid service is at 10 Cents if you buy $100.00 worth of time. I could not find this rate stated anywhere on TMobile's website.
I have had the wife on a T-Mobile prepaid acct for several years and she never used $10.00 of time per month... Now our daugter has realised Mom has text feature on her phone and suddenly the wife is consuming $25.00 + per month between voice and texts and that's with data blocked from her phone. So this means I could switch her to the $30.00 pm plan and give her 5GB of data as well. Sounds like a plan made for her:)
I suppose I could open up a "new" acct for the $30pm service and meantime the prepaid number will automatically run down thru usage and remaining minutes last 360 days. So I just hold onto the few remaining minutes for visitors... Might be able to ask TMobile then to switch over the 2 numbers so I keep both accts.