Legal analysis: the malicious overdraft of credit card reached more than 50,000 yuan, and the issuing bank refused to repay after repeated collection, which constituted the crime of credit card fraud and will be investigated for criminal responsibility by the court.

Legal basis: Article 8 of the Interpretation of the Supreme People's Court and the Supreme People's Procuratorate on Several Issues Concerning Amending the Specific Application of Laws in Handling Criminal Cases of Impairment of Credit Card Management, if the amount of malicious overdraft is more than 50,000 yuan but less than 500,000 yuan, it shall be deemed as the amount stipulated in Article 196 of the Criminal Law is relatively large; If the amount is more than 500,000 yuan but less than 5 million yuan, it shall be deemed that the amount stipulated in Article 196 of the Criminal Law is huge; If the amount is more than 5 million yuan, it shall be deemed that the amount stipulated in Article 196 of the Criminal Law is particularly huge.