I recently bought U from a long-term collaborator and transferred an extra 70,000 RMB to the other party. They did not return the money and said the chat records were deleted. I know I can check the WeChat and Alipay bills to clarify this, and I also know that Transcan can retrieve the transaction records for U. As long as they check, it will be clear that I transferred extra, but the other party seems unwilling to do so. I understand this as a deliberate refusal to return the money. What should I do now?