Bajaj Finance — Bajaj finance is threatening me to ruin my cibil score if I don't take overdraft facility

Once I got a call from Bajaj finance, asking for overdraft facility. I keep them asking for charges, and they kept on saying, sir please submit these documents then only we can tell you. They took all the documents. But never gave me product details. Finally once when they sent me the product details, I saw hidden and abrupt charges, I immediately cancelled that. After that they made my hell, I am getting 30 calls per day. Just now I got a threat call from Bajaj Finance saying if i don't take the Overdraft Facility, they will put a fraud charges against me, and I will never get any loan from any bank. Please help me.