Overdue summer credit cards have a 50% chance of generating interest refunds. Call the credit card center first and apply for a refund of the credit card penalty. If the bank doesn't agree, you can call the bank or complain at the CBRC, and the overcharged interest can definitely be refunded. Because of excess interest, liquidated damages, penalty interest, etc. If they exceed the red line, they can't get legal support and can complain back, but the possibility is only 50%. Banks need to check personal credit.