Do i have grounds to sue?

Hello, On 10th July i had applied for a loan with Fullerton India, and they intially approved me for a loan for 6,50,000 and they called me and started the process for documentation, throughout this, i followed their instructions word to word and submitted everything, the agent handling my case told me the documentation process is 100% complete and verification will be done, then when the verification happened at my house, i had to take a leave from my office, since nothing else was working but anyways they did the verification and all got approved, also they did a verification at my office with one of my colleagues and that was approved too. till now everything was good, but then they said the actual loan amount is 4,90,000, which i agreed to and they filed the paper and asked me to sign blank documents, which i was skeptical about but since the senior manager was very helpful and sincere i signed them and also gave them a blank signed cheque as that is the standard practice(what they said), but once the papers went back, i got a call from the senior manager that another verification was done and that came negative, as my office was in residential area, and they rejected the loan, now they are not responding to my calls and emails and they are not returning the signed papers too... I feel harassed, they have wasted my time and I can't apply to any other bank as i am marked for a loan of high value with them, I should mention that I had received a message of approval by the company. I want to know if I have any legal options? can I sue this company for mental harassment...