The Panasonic lady saying your problem is because the TV has a QAM tuner is very much like saying your car FM radio won't work on FM because it has an AM tuner in it. The broadcasts you're trying to receiver are all ATSC so only the ATSC portion matters. If she's saying Panasonic can't make a tuner that does both, then her excuse makes sense.
A good answer is easier with a clear question giving the make and model of everything. "The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw