Are you fairly confident that your installers knew what they were doing.
I have personaly watched 2 friends be told they could no way have line of site. Then with coaxing we found perfect line of site with no problems.
What caused your lack of line of site?
Do you have a dishnet system?
There are ways you can fool with that to find a line of site for 61.5?
I had to have a 2nd installer out because I was told the same thing. I did my homework in the meantime and determined I did have LOS. I was told if the 2nd installer wasn't able to perform the install, I would be charged a $45.00 service charge. Here is a thread that contains a Line of Sight calculator that you can use to check it out for yourself. http://www.satelliteguys.us/showpost.php?p=54432&postcount=193
I used a piece of posterboard and a protractor to accurately determine the correct elevation (I cut the posterboard so that all I had to do was look along the edge once it was level) and a compass to determine the correct direction. I had trees in that direction but the signal was at least 10 degrees about the top.