Bank closing account forcefully

Dear Experts, I have received a notice from Bank X that they will close my Bank account in 30 days as my profile does not match with the transaction. I replied to them asking such transactions and till today they did not provide me any transactions in written. in between they called me multiple times asking some personal information like where i work and how much i earn. i requested them if you need any information from me please send me a letter or email and i will get back to you as i am not comfortable sharing any information over the phone but they are not doing so. now they say i must convert my account to NRI account as i am abroad and i said the same thing that they should send me in written whatever they need and i will provide the information but they do not send anything. as i am currently abroad the letter which i received was opened by someone else and now including my family member think that i am involved in something wrong doing. So i said to bank either you provide me such transaction details or send me an apology letter. I don’t deny that i am not holding an NRI status as per the definition of 182 days stay out of India but the thing to note here is that bank never contacted me in the past requesting anything and sent such letter one day. from last 30 days i am dealing with different people of bank and they only talk about the conversion of account which i am not denying but at the same time i want them to provide such transaction details or an apology letter so i can prove myself clean. i would like to know if they close my account without providing any such details can i take legal action on them for spoiling my reputation? also this is my 8 year old account and i have distributed it among different parties for financial and investment purpose out which some i may not remember and i may lose my money when something come in from them. They have also called me in past two year and all the time I said that please send me in written which they did not do and then I assume these were same fake calls. After this issue I told them please send me everything only in written but they always call me. Is this not harassment ? i have already reached to their final level of escalation but no one replies and this morning i got last call and they said they will not provide any such apology and no transaction has been shared till today. its 30th day. my only fault here is that i am holding an NRI status but if bank had concern to this they should have approached me in requesting such information but sending such a threatening letter is not valid in my opinion and i would like to fight for it. Please guide me and may be you can assist me further with proceedings. Thank You. -M-