Background Check Issue: How to Handle a Date Mismatch with a Previous Employer?

Dear Team, I have been working in a bank for 6 months. Yesterday, the current company's HR called and informed me that my background verification was negative because the last working day of the previous company and the certificate date I submitted were mismatched. What should I do? Please suggest. I called that company, but they didn't respond to me.

Hi, Please find out from your previous company's HR regarding the difference in relieving dates. Have you manipulated the relieving letter and given the wrong date? If not, get a proper explanation from the previous company and submit the same to the current employer.