Answer: Disculpa, hay algo mal con mi comida, me lo podrías cambiar por favor?
(If you want to add examples):
Disculpa señor, mi orden está mal, me puedes cambiar la agua con un vaso de soda?
Explanation: The following are in Spanish, here’s the English version.
1. Excuse me, there is something wrong with my food, can you please change it?
2. Excuse me mister, my order is wrong, can you switch the water for a cup of soda?