The reasons for the higher interest rates on unpaid credit cards of Mongolia Commercial Bank may be due to the following aspects:

1. Interest rate level: The interest rates of credit cards of different banks may be different. If Mongolia Commercial Bank sets a higher interest rate, the interest on the unpaid full amount may be correspondingly higher.

2. Overdue interest rate: The interest rate for overdue credit card payments is usually higher than the normal interest rate. If the cardholder fails to repay on time, Mongolia Commercial Bank may calculate interest based on the overdue interest rate, resulting in higher interest on the unpaid full amount.

3. Calculation method of interest on the unpaid full amount: Different banks may have different calculation methods for the unpaid full amount of interest. Mongolia Commercial Bank may have adopted a higher calculation method, resulting in higher interest on the unpaid full amount.

4. Other fees: In addition to interest, credit cards will also charge other fees, such as annual fees, cash withdrawal fees, etc. If Mongolia Bank's other fees are relatively high, interest on the unpaid full amount may increase.

It should be noted that the above are some possible reasons. The specific situation may need to be determined according to the relevant policies of Mengshan Bank and the credit card contract. If you have any questions about specific interest charges, it is recommended to consult Mongolia Bank customer service or read the credit card agreement.