What is the biggest mistake customers make?

Is this a really bad mistake to make on the job?

• I was calling patients to remind them of their appointments, and I called this lady to remind her that her appointment was scheduled for 4:30pm. She immediately said no, that her appointment was at 6:00pm. I tried explaining to her calmly that it in the system it says 4:30pm but it was useless reasoning with her, so eventually I said we can schedule you in for 6:00pm if you'd like. She was upset afterward, and I think this is a bad mistake to make, particularly because there's alot of pressure to get new customers and keep them. At my old job, it wasn't like that at all.

• Answer:

  It sounds like the mistake was hers and you handled it as best you could.