On his podcast, Clark Howard answers real reader questions on money, credit, debt, retirement, travel, and more, along with co-host Christa DiBiase.

Clark's answer: Here is the deal – and this is going to sound cynical – but when you sign up for a technology service, they bill you starting on day one. When you cancel, however, they tell you your service stays active until the end of your billing cycle. In other words, they get you coming and going. This isn't just a T-Mobile issue; it is pretty much universal across the tech industry today. You pay from the very minute you start with them until that final billing cycle wraps up.

To work around this in the future, check when your billing cycle ends and time your transition accordingly. Give yourself a buffer of about four days before that end date to complete the cutover and switch your cell service. That way, you avoid paying for two different providers for any extended period of time.