Case of loan formation
This situation can be counted as usury.

Detailed description:

1. Loan amount 13000 yuan, overdue for more than half a year, overdue fee plus principal has reached 13000 yuan.

2. Usury refers to a form of loan in which the loan interest rate is much higher than the market average, and there are usually potential risks and unreasonable charges. According to the information provided, we can analyze the following points to determine whether it belongs to usury:

A. If the loan is overdue for more than half a year, the overdue fees and principal have exceeded the original loan amount, which means that the borrower needs to pay extra fees exceeding 100%.

B. The repayment amount of the first six installments is about 6,543.8+0,000 yuan, but the expenses caused by overdue for more than half a year are 6,543.8+0,000 yuan and 3,000 yuan more than the repayment amount of the first six installments, which shows that the overdue expenses are high.

C. According to conventional standards, usury generally refers to the characteristics of high interest rate, unclear contract terms or hidden manufacturing costs. Despite the lack of specific interest rate information, the overdue fee is much higher than the loan principal, which can be regarded as an indicator of usury.

Summary:

According to the above analysis, this situation can be identified as usury. The overdue expenses incurred by overdue for more than half a year are much higher than the original loan amount, which is beyond the reasonable range of the borrower's ability to pay.

Extended data:

Usury refers to a form of loan in which the lender charges the borrower high interest or unreasonable fees. Usury is usually considered illegal and fraudulent, and is strictly restricted by law. In this case, the borrower can seek relevant legal aid or communicate with relevant institutions to safeguard his rights and interests.

Note: The above answers are inferred from the information provided, assuming that there are no other factors affecting the specific terms and interest rates of the loan contract. If there are more details, there may be different conclusions or suggestions.