Disgusting service by Mc Donalds

I downloaded the McDonalds app . They advertised specials that you have to redeem at the kiosk . So based purely on the specials offered i went down to Parklands mc donalds . I activated the special at the counter after placing the order . The crew member that was taking my order refused to use the coupon code and told me to f*** off if i have a problem with it . She then slammed the window shut in my face .after profuriously knocking on the window she then re opened it i tried then to enquire normal prices on different meals but she refused to give me any information . So i just made a order for 3 cheaper meals . When i got the meals i immediately checked them , i was given half full chips and missing a burger . I then knocked on the window to rectify the problem but they refused to open up and help me . I dont know if this is the normal treatment you guys give your customers but i feel as if i were ****** .