...Good line of site,but they said I had reflection problems. Any experience with this?...
They might be talking about terrestrial interference. It's difficult to prove with a signal strength meter which is what most of those guys have. You really need to have a spectrum analyzer to determine that. Always possible the guy got frustrated and started making stuff up though.
Terrestrial interference is in-band noise, although this is much more prevalent with
C-band, particularly in America where flight and maritime altimeter/radar is about 3.1-3.7 GHz. Sometimes those frequencies resonate up into the C-band range. I have seen several occasions where L-band noise (950-1450MHZ typically) ingresses into the system through crimp style or otherwise loose or bad connectors. Additionally, any electrical arcing can cause TI. A/C units kicking on, street lights - I once troubleshot a system that it turned out to be a bad spark plug in a lawnmower. That was a month of my life I'll never get back.