Bangalore Debt Collectors threats and harassment to senior citizens

We seek expert, accurate and trusted legal advice regarding a debt recovery agency that have again started sending recovery agents to our house for some credit card dues taken by our daughter in Dubai in 2015. She is not here in India and we are her senior citizen parents. They come without any proof, they show photocopied Letter of Authority from these UAE banks which are expired 2-3 yrs back and they speak rudely with threats. They also have illegally accessed police passport verification data to trace our addresses. We want to know is this legal? Also, they said they will legally file a case on us. The credit card was issued outside India, outstanding is of a UAE bank and last we checked with our daughter - she is not aware of any dues on her cards she cancelled them already before leaving UAE in 2016. She is now settled in USA and due to family problems from her husband is not talking with us also. In the meantime these rowdies are harassing us two senior citizen parents! Is there jurisdiction? Also if Indian branch of this UAE bank is there, can Indian branch prosecute on behalf of the UAE Branch? We have filed police complaint but calls are still coming and they come home now. We are very scared old people and we need legal help to file case on them but they say they are only a law firm. Can anyone help us what to do?