BrokenPine

I have a huge problem on my hands. My crew and I were hired to film a commercial for a large company last week and we came out and filmed it all in three days. We had to travel a lot to get from one location to another throughout each day and often didn't get back to the hotel until after 1 AM and would have to leave by 4 that same morning, so we had little time to sleep or review footage. After it was all said and done and we had finally returned home after the last day of filming, I started to upload footage to begin editing. That's when I noticed the most horrific problem I have ever had in my years of filming. The audio taken while filming the interview was completely screwed up. I don't understand what happened. I filmed this particular project with a Sony a77 and a Sony a99 because they fit the commercial type well and I was recording the audio using a Sennheiser wireless mic attached to a Beachtek DXA-SLR Pro HDSLR Audio Adapter that was connected to my a77. I have never had issues with it before. I had the decibles set well and had headphones plugged into the audio adapter, so I was monitoring the sound the whole time and everything sounded great. But when I went to play back the clips, the audio had the loudest whine you have ever heard and you could barely hear the person talking. It couldn't have been the batteries beause they were relatively new and even if they weren't, there is no way in my opinion that I could have heard everything through my headphones if the batteries were bad. I just don't get it. Fortunately, I had a Rode shotgun mic recording on my a99, but even it isn't the greatest right now because for whatever reason, the audio has a ton of hiss in it. Could somebody please help me fix this? I can't just drive hours to go back and tell them that I screwed up the interviews and need to redo it. This is my first time with this new client and so far they have been impressed with everything. To do that would make me look realy bad and give a terrible first impression. What happened and can we do anything about it? And if not, is there a way to at least get the shotgun mic to sound much better without the loud hiss? I have recorded off of these SLRs before and never had this problem, so I am baffled and desperate to fix this issue. Any help would be greatly appreciated.