Frame And Members problems of the 2005 Nissan Xterra

I purchased an 05 Xterra in September. At about 6,000 miles it developed a squeak in the front end. I took it back to the dealership 5 times and the last time they were able to locate the noise and stop it. I asked the service writer what the problem was and she told me I didn't want to know. I pushed for an answer and was told that the frame on the passenger side front was not welded, causing the metal to rub together and squeak. She also told me that the washer fluid tank was rubbing the frame. The only thing written on my service order was the washer fluid tank. I don't know if my Xterra has a faulty frame or not. The consumer line for Nissan has a file number for me but I have made repeated attempts to get a call back from them with no response.