legal analysis: not illegal. According to the current credit card regulations of major banks, the credit card limit will be restored as soon as the cardholder repays, that is, as long as the cardholder's card is normal. If someone else repays the money in the credit card instead of the cardholder, it can be swiped out immediately. In this way, not only the repayment record, but also a consumption record, coupled with some small consumption, can enable cardholders to increase the credit limit faster.

legal basis: article 673 of the civil code of the people's Republic of China

if the borrower fails to use the loan according to the agreed purpose, the lender may stop issuing the loan, recover the loan in advance or terminate the contract.

article 674 the borrower shall pay the interest within the agreed time limit. If the time limit for paying interest is not stipulated or clearly stipulated, and it cannot be determined according to the provisions of Article 51 of this Law, if the loan period is less than one year, it shall be paid together with the loan; If the loan period is more than one year, it shall be paid at the end of each year, and if the remaining period is less than one year, it shall be paid together with the loan.

article 676 if the borrower fails to repay the loan within the agreed time limit, it shall pay the overdue interest in accordance with the agreement or the relevant provisions of the state.