Eish, I don't know

Went to the KFC at El Ridge shopping centre to order food (Month End). Got there and the drive through was very slow. When I finally got to the window, the girl told me that I had to wait 20min for the chicken to cook. I paid and asked for a manager at collections. She had the lame excuse that the one oven broke and that is why the chicken is delayed - so how is this my problem, do they don't know how to plan, if not, why is she a manager? When I told her I will complain she was like