In your case, when the bank mortgages the real estate, especially when the other party gets the title certificate of a third party, it must be signed by the bank. At present, there are great negligence and loopholes in the audit behavior of banks, and they can be required to bear corresponding responsibilities. If there is really no other way to realize the rights and interests, you can consider entrusting a lawyer to sue. At present, there are few lawyers in Zibo on our website. I suggest you go directly to the local law firm to consult a lawyer and see what measures are better.