When she received the phone call, and apparently a mailed letter as well (which we don't actually see), she is not confused or drugged-up. The fact that she needs to fit into the old red dress from her youth is what causes her to take the pills which in turn cause all those hallucinations.
So when she ends up all crazy-looking at the TV station's offices, why do they call the cops when she actually has won the contest to become one of the people on the show? They just seem to shake their heads and look at her with fear and sadness. Why didn't they just explain that it's only at so-and-so date and time? And did the lady just show up there randomly? My impression was that the day had finally arrived, and she was going there just like she planned, only that she had become all confused and scary-looking from the drugs?