If you like T-Mobile, and want to be sure your company stays T-Mobile, I suggest one of their own-brand Connect prepaid plans.
They have what you're paying $25 for, for $15. MVNOs just aren't very appealing any more. The big 3 have dropped their prices.
Connect by T-Mobile: Affordable Phone Plans Starting at $10/Mo.
Connect by T-Mobile is a plan to connect all Americans, offering a $10/mo. prepaid phone plan that includes unlimited talk & text and high-speed data.
prepaid.t-mobile.com