Everyone is the same. The billing date is the total amount of your consumption last month, and the repayment date is the day you should repay. For example, your billing date is the 8th and the repayment date is the 26th. The amount you consumed on May 8th must be paid off on the 26th of June, which adds up to 51 days. If you consume "It's the 7th" just one day before the billing date, then you will have to pay it off on the 26th of the month, so it will take 20 days. Do you understand?