If any recovery agent is using abusive language, threatening then that's a separate offence and as taking loan and not re-paying it. Both cannot be equalize and logic in not justified.
Also loan default may be sometime genuine and what if a person gone bankrupt?
One needs understand that if a person has defaulted bank can only take possession of the property mortgaged and in case of personal and credit card loan bank and other sub-prime loans lent on high interest to make quick bucks they without doing the proper background verification.
I strongly believe the defaulter should make his best attempt to re-pay and if unable to do so he should file a bankruptcy and also banks should deploy only legal method for recovery.