Mcdonald's - Escondido

I visited McDonald's today and went through the drive-thru to order a large Coke. After paying, I received the drink and drove away. However, when I took a sip, it tasted like diet Coke. So, I parked the car, went inside, and poured it out, filling the cup with regular Coke instead. Then, I decided to order a hamburger. When I approached the counter, the manager confronted me and nearly accused me of stealing the soda. I did not appreciate this attitude from the staff at the restaurant.