How can I convince the US Immigration Services that I deserve all right to be an US Citizen?

Hi I'm an legal resident in this country. I've been living here in the United States for 15 years. Last year in 2009 I finally filed to become a U.S Citizen. Now, they finally sent me a later that said right now I'm ineligeble. And requested $ 605 from me again. I don't don't understand, All I was waiting for is the letter for my ceremony, that were promised by Immigration agent. But, instead after all of that waiting, chasing them around I've received an ineligeble answer from them. Why? I don't know because I did everything by the book, I've sent them all necessary information, went to all of their interviews, and took the required tests and Pass, and was scheduled to received a letter in 45 days in the mail for my Ceremony to become a US Citizen. What should I do, after I've already spent money and now they're require for me to spend extra $605 just to review my application again in 30 days. With the way the economy is. I don't have that kind of money right now. So, What should I do?