If you knowing the law properly then you should challenge the same before the court where the case is being prosecuted. You cannot question the court sitting outside about its function that how it accepted the case.
On receipt of summons it becomes your duty to appear before the court either in person or through your lawyer, you can vent out all your grievances before the court in the form of written statement and by deposing evidence during trial. Are you denying the loan itself, if so on what reason, if your reason to deny the loan itself will be based on some reliable issues, then you may challenge the case with the help of it.