A change to T-Mobile's billing methods means it'll want to see the color of your money before you've barely had time to play with your new handset. Normally you'd enjoy a liberating spell of non-topping-up telephonic joy before the cold, financial reality of the money being sucked out of your bank account. However, from the 20th of this month, new post-paid customers will be expected to trump up in advance for the recurring part of their bill. Don't panic though, while the first bill might feel a bit heftier (as it includes the pro rata amount for the month, and the next full month,) you're still paying the same amount over time. But, if you're used to the old method, it might come as a bit of a shock when that first magenta envelope hits your letterbox.