Problem with Bajaj Finserv regarding Insurance againest Personal Loan

Hi Sir, I have taken a loan from Bajaj Finserv in the month of Dec-2016, while taking the loan they asked me to sign on insurance docs, But I refused to take insurance so they told me please sign on this docs and later you can cancel the insurance you will get 100% premium (Insurance premium amount is 35000/-). But when I tried to cancel the Insurance they didn't accept it, So I called to HDFC life customer care to cancel the insurance, they said they can't take request directly as it is from third party (BAJAJ) So I sent mail to bajaj representative (who coordinated with me while taking loan) he replied saying that In a year you can cancel you will get 100% back. Also I am keep on sending requests to customer care, so after some months in July-2017 they accepted for surrender but they given only 12,700/- and saying that you should raise request with in free loop period to get 100% premium back. My question is I sent the mail with in the free loop period to cancel the insurance but they didn't accept it and now they are saying its not possible to give 100% premium. And one more big mistake from their side is, I have taken loan on 07-Dec-2016 but they send Insurance premium receipt with date of 30-Nov-2016 How it possible that before taking loan they made premium for my insurance. I sent many mails to them but no response and they forcible closing my requests. Please help me sir, Can I proceed legally.