Misguidance from icici bank

Respected Sir/madam, I'm Bhaskar, I applied for Loan against Property in ICICI bank. a customer support executive called and informed me that I'm eligible for Pre-approved loan. and wanted me to pay 6000/- INR i the name of processing fee. before payment, i asked the customer care executive twice and thrice what if my loan gets rejected. he said I met all the requirements for the loan like area, documents requirements, CIBIL score. i paid for it, they sent me a sanction letter in which it is mentioned that fee is not refundable. They also mentioned that further procedure will be started only once the fee is paid. Today, property assessment verifying guy told I don't meet the required documents for sanction of loan. 1) my question is how a customer would know before payment that the fee is non refundable? 2) How a bank can ask for fee at first, then they give a sanction letter, then they say you are not eligible. ? They would have done the document verification process at first and could have told whether I may or mayn't eligible for loan. The sad story of middle class person is they fall prey for all these kind of tricks played on them. the need of money make them to accept everything, and some get lost everything, some may end their lives.