If you belong to a usury company, you dare not sue, because usury itself is illegal and not protected by law. You can not return the illegal part. According to the contract law and other relevant laws and regulations, you should calculate the principal of the loan with the money actually received. (Article 200 of the Contract Law stipulates that the loan interest shall not be deducted from the principal in advance. If the interest is deducted from the principal in advance, the loan will be repaid according to the actual loan amount and the interest will be calculated. )