McDonald's

There's an Employee Whitney who is extremely rude to me every time I go to this establishment. I've heard her saying to another employee "I can't stand her" talking about me. I do not personally know this lady and I do not appreciate the way she acts when I go thru the drive thru. I get a iced coffee with extra Cream and extra syrup and extra liquid sugar. She sends it out the window a coffee that is pretty much black coffee. When I ask for extra cream and all i expect to get what I pay for. She does this to me Everytime. I've had enough of it. Something needs done at this point. I'm a local who enjoys McDonald's and I'm a loyal customer. I will no longer go here as long as I'm recieving this kind of treatment from your employee whom I do not even know. She also tells me my coupons on my mobile app have already been redeemed when they haven't. She's tried to charge for the car in front of me order and I have to break it down to her what I ordered and what it costs. If my order Is $5 and some change I gave her $6 and she will tell me I didn't give her enough money. I told her to count it again. It's every time I go here that there is an issue with her.