Can a bank mark lien of Credit Card dues against Gratuity credited in Salary account

I am an ex-employee of a bank and the bank is processing my final settlement. In the process, the bank has credited the gratuity into my salary account as a process of final settlement. The remaining Full and final settlement is pending for payment from the bank side. I also happen to hold the credit card of the same bank and that is not a staff card. Bank has forwarded a letter stating that the entire amount outstanding has been marked Lien against my salary account, as a result, I am unable to service EMI and other liabilities even though I have money in my account. I have been subjected to harassing abusive calls from representatives of other financial institutions, they are sending collection agents at my house and jeopardizing my goodwill. I had written to my bank to remove the lien and also offered to provide them with more than a serviceable amount against my credit card dues through a post-dated cheque as I have received date confirmation from the bank's HR team regarding the date of the final settlement. but they are adamant and unwilling to cooperate This has not only left me in a situation of mental trauma but at the same time helpless . I, therefore, request advise in this matter