You can only go to court to sue for unjust enrichment. Take the bank's payment records to court to sue. You can write the complaint yourself. The following is for reference only:
Civil litigation for unjust enrichment
Plaintiff’s attorney: Attorney Zeng Yongqian.
Plaintiff: Liu × Xue, female, Han nationality, born on this day, address: XXXXXX.
Agent: Zeng Yongqian, lawyer at Guangdong Fanli Law Firm.
Defendant 1: Feng XX, the holder of the UnionPay "Golden Harvest Baotong Card" issued by the Agricultural Bank of China, with the card number 95599 8008 13978 XXXXX.
Defendant 2: Agricultural Bank of China, Dongguan Branch, domicile: No. 30, Hesheng Road, Guantai Road, Chengnan District, Dongguan City.
Litigation request:
1. Judgment that the second defendant shall inform the first defendant in writing of the UnionPay card "Golden Harvest Baotong Card" card number 95599 8008 13978 42311 issued by the Agricultural Bank of China. name, identity, address and contact information.
2. The two defendants were judged to be jointly and severally liable for returning RMB 8,900 to the plaintiff.
3. The litigation costs of this case shall be borne by the second defendant.
Facts and reasons:
During April 2006, the plaintiff’s husband’s mother discovered that the UnionPay card “Golden Harvest Baotong Card” issued by the Agricultural Bank of China with the card number 95599 8008 13978 4231 , and later took the card home and mixed it with the UnionPay card "Golden Harvest Baotong Card" issued by the Agricultural Bank of China that the plaintiff applied for and held. From August to September 2008, the plaintiff used the password of the UnionPay card "Jinsui Baotong Card" issued by the Agricultural Bank of China managed by the second defendant to use the ATM machine located at No. 18 Shatai 2nd Road, Shatian Town, Dongguan City, in five minutes. This time, RMB 8,900 owned by the plaintiff was mistakenly deposited into a bank card with the card number 95599 8008 13978 4236545.
After the case, the plaintiff discovered through on-site operations that the ATM machine set up and managed by the second defendant at No. 18 Shatai 2nd Road, Shatian Town, Dongguan did not recognize the password when handling customers’ automatic deposit services. After verifying the UnionPay card password, randomly enter any set of six-digit Arabic numerals to handle automatic ATM deposits. It was precisely because of the above-mentioned fault of the second defendant that the plaintiff mistakenly deposited all his money into the UnionPay card "Golden Harvest Baotong Card" held by the first defendant with the card number 95599 8008 13978 42311.
The plaintiff repeatedly requested the second defendant to inform the first defendant of his name, identity, address, and contact information and to return 8,900 yuan to the plaintiff, but the second defendant refused. According to Article 92 of the "General Principles of Civil Law of the People's Republic of China" and the relevant provisions of the "General Principles of the Civil Law of the People's Republic of China", in order to protect the legitimate rights and interests of the plaintiff, we hereby file a lawsuit with your court and request a judgment according to law!
I hereby convey
Dongguan Municipal People’s Court
Person shaped by:
Agent: Zeng Yongqian, Guangdong Fanli Law Firm Lawyer.
September 2008
If you have any questions, please ask. If you are satisfied, please adopt. Thank you.