Great Clips review: Online check in not honored

I go to the shop at Pine Corners in Tyler TX and today I checked in on my phone and it said 18 minute wait. I stopped at the Dollar Tree then arrived when the wait should have been less than 10 minutes. The girl told me there would be a 30 minute wait. I told her I checked in online and she said it didn't matter. She proceeded to check in someone who was sitting in the lobby and told me there were still 2 ahead of me. there were only 2 besides me in the lobby. I told her I didn't have time to wait and I left. Why allow the online check in if you are not going to honor it. I love it because I always know what to expect. I thought this was a very rude way to treat customers.