I can give you some explanations for credit card bills and late repayments.

First of all, a credit card is a short-term loan instrument, and the cardholder can spend within the limit preset by the bank. Every month, the bank will send a statement to the cardholder, which will show the consumption amount and minimum repayment amount of the month. If the cardholder does not repay in full within the stipulated time, interest and late fees will accrue.

When a cardholder makes a late payment, the bank will calculate overdue interest based on a certain interest rate and may charge late fees. The longer a payment is overdue, the higher the interest and late fees will be. In addition, banks will also report overdue records to personal credit records based on certain conditions, which may have an impact on the cardholder's personal credit evaluation.

According to your description, if you only used more than 10,000 yuan on your credit card at the beginning, but you need to repay more than 50,000 yuan after one year of overdue, the possible reasons are as follows:

1. Calculation error: It may be that the way you calculate overdue interest and late payment fees is wrong. You can double-check how your bill and related fees are calculated.

2. Accumulation of interest and late payment fees: After overdue repayment, the bank will calculate overdue interest based on a certain interest rate and may charge late payment fees. If you don't make timely payments, overdue interest and late fees will accumulate, causing the amount due to be repaid to increase.

3. Applied for other services: Sometimes, banks will proactively provide cardholders with other services, such as loans, installment payments, etc., based on the cardholder's credit status and needs. If you apply for these services during the overdue period, the corresponding repayment amount will also increase.

In addition, the specific repayment amount will also be affected by the credit card's interest rate, installment payment, additional services and other factors. In order to accurately understand your situation, it is recommended that you contact China Everbright Bank’s customer service personnel directly, and they will be able to provide detailed explanations and assistance.