What can I do to resolve this problem?
Be more specific. Did someone actually come out and tell you there is a line-of-sight problem? I second what Brad said. Ger a second opinion. If it is a difficult installation some installers will say "no line-of-sight" rather than do whatever is needed. Contract installers sometimes are not paid enough to do more than the simplest installation. This is another reason to use a local dealer if possible. Since they are also getting commission and residuals so they have a lot more incentive to get it to work.