Employee Termination Indian Pvt sector Bank - Where should I approach to challenge my termination?

I used to work with a Indian Pvt sector Bank in West Bengal. I had joined the Bank in September 2011 and worked till March 2015. I have performed my underlying job very well and no memo or any HRaction was taken against me during the period. In April'2014, since it was beginning of the financial year I approached my BM and other concerned authority and Regional HR Manager to get transfer to or nearer to my home location in Bihar. Apparently it seemed that they were not happy with my request though they agreed to transfer me and asked me to initiate a mail to my HR and superior authority.

I was in constant follow up with my Regional HR Manager for transfer, in the meanwhile I continued to work in the same Branch, In the month of March 2015 my Regional HR Manager and my Cluster Head told me, they are not able to put me in a suitable role at my Home location/nearer and asked to put my resignation, they threatened me otherwise I will be terminated, I refused to put my resignation without any reason, also I informed them ,that, " I am suffering from Spinal infection and advised a complete bed rest at least for a month", but they refused to grant me any medical leave and asked me to put my resignation and search for it new job. I urged and explained them my inability to move immediately out of station to search for a new job because of Spine collapse, but they refused to grant me any medical leave and humiliated me.

Indeed a termination letter was issued to me on March 5,2015.The reason for termination is not given and they have mentioned the extant of employment agreement for termination. I have received the 90 days salary in lieu of the notice period that too in installments and after rigours followup of four months. 

Where should I approach to challenge my termination?

Please correct me if I am wrong.
If your wages (basic pay) is less than 10,000 you will be a workman and you can raise a industrial dispute. You can go to your Labour Commissioner.

Dear Sir @ Nathrao,

Thanks for your response. It is true that I am still suffering with spine infection, which actually is an infection caused by Bone Tuberculosis,and I have all medical/treatment documents and report with me, though it was detected in the month of January'15 and I was advised bed rest at least for a month by the doctor, but considering the responsibility of job I continued to attend the office and delayed my leave request till the end of Financial Year 2015,but suddenly in the month of March 2015, my Regional HR and superior authorities started pressurising me to put my resignation which I refused, moreover there is nothing to correlate between my transfer and my leave request, even I was called by my Regional HR Manager in the last week of February 2015 to visit and meet the Cluster Head of Patna, Bihar as there was a position vacant under him and suddenly after few days same HR asks me to put my resignation.....isn't it ridiculous.
I have the copies of all mail followup.

Dear Sir @ Prachanda,

My basic salary was 18500 and gross monthly emoluments was Rs 51000.00.

Thanks & Regards
Rajeev Kumar Ray.

Dear Rajeev,
You have not mentioned about your designation in the Bank. Whatever it be, you are a person employed under the West Bengal Shops and Estt, Act,1963. From your narration, your termination seems to be illegal. So, you can prefer an appeal under Sec.15 of the Act immediately. For the procedural formalities, go thru the relevant Rules and take the advice of a trade union or an advocate specialised in Labour matters.

Dear Rajeev,
It is very likely that the termination decision was taken by the local management due to some grudge against you.Approcah your top management--write directly to the Managing Director--with full details.Do not lose any time.I have seen such termination orders are taken back even in central PSU.Your's is a private bank.Hiring and firing can not be at the whims of a middle level manager.You must fight ! All the best.

Dear All
Thank you very much for your valuable responses.
Further would like to inform you that I was positioned as Back Up Branch Manager in a Manager Grade. Though my nature of job was supervisory and monitoring the Branch operation and compliance but I did not have authority to sanction leave or to promote anyone
Regards
Rajeev Kumar Ray