Education loan defaulter's guarantor liabilities

My father became guarantor for his colleague's kid education loan of 4lacs in year 2008. However rules were clear about no need of guarantor for an education loan up to 4lacs. Still bank asked for a guarantor and my father signed. The colleague has not paid the amount back to bank. His account is now declared NPA. Bank is now querying my father stating that defaulter's phone is not reachable. Bank suddenly decided to prohibit withdrawal of money from my father's savings account, which is in the same bank. They have seized around 40000 rupees in the savings account. Note: My father so far have not received any legal notice being a defaulter's guarantor. 1.) Is it legal for bank to block withdrawal of amount from savings account without any written communication and legal notice? 2.) Was bank not wrong to ask for guarantor when the rules were clear about having no guarantor for education loan UpTo 4lacs? 3.) Shall I file a RTI asking for legal notice based on which bank took this decision? Please provide me remedies to come out of this problem. The defaulter has enough assets and properties to pay back the loan but he has decided not to pay anything to bank assuming that ultimately loan would be written off. Please help.