Most embarrassing moment in a drive thru

Yesterday morning I drove to McDonald's in Kenako mall drive through in Port Elizabeth, on their operational decals they open at 07:00. I was there at 07:05 and no one attended to us, I drove around the drive through second time and I noticed there were people inside then I stopped by the window. A lady opened and I asked if they were opened, she answered Yes they were but no one can take my order and asked why. She said "I don't know but let me call my manager". 5 minutes passed and the manager by the name Mavis peeped out of the window and I politely asked if they were operational, in her annoyed response she told me she just shouted at her staff for being late and left me standing there. No apology and no way forward, I then asked from a lady that remained stunned if can place an order and she also rep**** confused that she doesn't know what was happening. In all, I stood there for 20minutes without being attended to and finally I left to the nearest McDonald's branch.

If this is how they operate, why do they then have thru? It's meant to assist people who are in a rush to beat morning traffic and it did not work for me. Most embarrassing moment because I had my colleagues who visited me from out of town who wanted a quick morning coffee and a wrap.