Horrific service

I visited McDonald's Silverwater Crossing in Silverton.Ordered 4 mcflurries. The order was correctly repeated and I paid via point of sale. Stopped at the next window and received only 3 mcflurries. One mcflurry was standing separate from the other 3. Thus, they knew that they made a mistake. Didn't apologise and justinformed me to pay for the 4th mcflurry. I told the cashier that I ordered 4 and that it is not my fault they only charged me for 3. I was willing to pay for the 4th one, but said I will pay by card. I was requested to pay inside the shop. What is the use for drive-through? I am inconvenienced and was told that if I don't pay, I'm *****ing. ****! They call me a *****! **** you McDonald's. I will never support you ever again.