Lien amount in joint saving account with mother

Respected sir, recently we opened joint saving account in ICICI bank with my mother as my mother is Widow, 61 years old and her medical conditions are not good so she can not go bank every time, she make me primary holder of joint account even when we opened a/c my mother gave the cheque of 12500 for open account and all are money of my mother. Yesterday they lien all amount from our account they give me reason my credit card payment is due from last 8 yrs which i don't! I have all the medical reports of my mother is going under treatment. I have a question Can a joint bank account between a mother and son be levied by a Icici bank when only the son is the debtor? What are the RBI rules for lien amount for joint a/c and what should we do to get my mother money back? Pls reply.