Book urgent care & walk-in clinics near me in Frederick, MD

I had a 5:15 appointment and when I checked in I was not told that the office was 90 minutes behind. I waited till 6pm and when asked I was told I was next. The next person taken was a walk in that arrived after me. I then waited until 6:50 to be taken back. Didn't leave until 7 pm. A two hour appointment with reservations is unacceptable especially since I was not told. My app was a follow up and I would have rescheduled given the information of the long wait. Better communication would be appreciated