Perthetic behavior of staff members

I visited the nandos drive through around 5 this afternoon. I always check the order prior to me driving off as they usually don't include everything. Upon checking, I found that there was no extra sauce in my strips and rice or extra feta( this was requested when I initially placed the order). I then reversed into the drive through again and advised the lady at the window that there was no extra sauce in my food as requested. She completely disregard what I was saying to her and ignored me. I even pressed my car hooter and she continued ignoring me. Another lady comes to the window and rudely tells me, can you take a chill pill and wait! This incompetency and attitude of your staff members is totally unacceptable, it's lot like we getting the food for free. Not the first time I received this level of service from the nandos in Trade Route Mall. Perthetic!