Jet Blue / not respecting a voucher and flight delay

I was scheduled to fly Jet Blue FLT 174 from San Jose to New York on Sep 1, 2006 at 10:35pm. We were made to wait for 3 hours before we were told that the flight would not leave until the next day since a flight attendant was sick and they could not find a substitute. So then we were asked to queue up to get our free round trip compensation vouchers. I stood in the line for another 2 hours to be simply told that the confirmation number on my boarding pass would suffice to ask for a voucher when I travel next. Since I was a San Jose local I didn't ask for a hotel voucher but others were being provided with vouchers as well. I called Jet Blue to get my free return flight on Aug 4, 2007 and was told that their system showed that FLT 174 flew out on time and there was no record saying that passengers were made to travel the next day. The system actually says that the flight with me in it left on time, which is unbelievable. I know when and what time I traveled. I feel simply cheated and this is bad faith on Jet Blue's part. I talked to a supervisor who was very rude. I would Jet Blue to keep to their word. I would like a document suggesting what time FLT 174 actually left and that it was not delayed because what I was told was a complete lie. Did anyone face a similar problem?