T-Mobile cracks down on billing trick used to stack discounts and credit card rewards

TL;DR

• T-Mobile has closed an AutoPay loophole that allowed customers to claim discounts while paying bills early using ineligible methods, such as credit cards.
• Going forward, customers who use such methods will lose the $5 per line discount for the next billing cycle.
• Discount eligibility resets each month, but requires full payment through eligible methods, such as linked bank accounts or debit cards.