Since your father never bothered to participate in the cse and record his objections and never expressed his objections before court especially after receiving summons from court then the court has rightly sert him exparte and passed the judgment in favor of the plaintiff.
How did you express before court that you would be willing to settle this amount?
If you have not filed any poetition to this effect then the court will not accept any oral submission.
You should have fought this case instead you have kept quite while the proceedings were going on in the court of law, now what is the use of grumbling after everything has left your hands?
You take a second opinion from a different lawyer by producing the relevant case papers before him and proceed as per the suggestions made
You can prefer an appeal before high court if it is worth enough