The Contract Law stipulates that the debtor uses fraud, coercion and other means to make the guarantor provide a guarantee against his true meaning. If the creditor knows or should know the facts of fraud or coercion, the guarantor shall not bear civil liability. I don't think you can explain the collusion between creditors (banks) and debtors (lenders). The result of handwriting identification can only show that the debtor may have forged your handwriting or the seal provided a guarantee to the creditor in your name. The bank can say it doesn't know.