1. The bank may have reported to CIBIL and have an entry of your name in the defaulter's list.
2. No what they can do is only use pressure tactics and trouble you to get the money b y way of threatening calls or intimidating your relatives and family.
3. Your legal option to deal with this situation is.
a) . File a police complaint, by giving the details and the mob.nos of the caller, if possible with names.
b). next time when they call you tell them that you have initiated legal step and will be going ahead with it.if the bank wants it has to recover it from you legally and for that it should approach a court and send you summons.if it happens you will get enough time to defend and to pay back if you desire so. But usually credit card disputes are written off as bad debts and the banks report it o cibil which will get you a negative/bad credit score, So to avail future loan or to maintain your credit score you will be forced to pay it off completely.
4. If bank approach you for settlement, it is not advised to go for a settlement as unless and until you pay off the full amount what reflects in CIBIL record to the bank and insist them to delete the the name from the defaulters list in CIBIL , your credit score will not be corrected.
finally get the help of an advocate if you receive nay notice/summons which may not happen.
if you feel the threat and trouble is increasing send a legal notice to the bank for the same.There is guideline issued by RBI in terms of recovery fro banks and the method they can take and the recovery agents are not approved by RBI. The recovery agents are private agency entrusted by bank .