Our cable is the worst service company going. They have a whole city contract and pretty much do as they please. My only other options are Sat and OTA. Done Sat (voom) and more channels than I ever watch plus little HD without voom. No local HD. So I watch OTA locals and cable for 14 and up.
Turns out the guy who installed my antenna knew the problem exactly as you described, but cable co is NO help.