Bad service quality and incorrect orders

Yesterday me and the family went for a drink after being in the sun half the day. It was around 06:00. Chantel was our waiter at the time. I ordered a chocolate milkshake instead i was given an strawberry milkshake due to them not having stock. My sister then said she will take my milkshake instead of me drinking this. However this does not change th 1. Waiters should not assume but rather return to the table and ask whether they would rather want something else. 2. Overall the service was pathetic and way under standard - I know this since I work at a Spur myself part-time.