good food, slow service around lunch time

A group of friends (9) went to have drinks all seated at the same table. One group of 3 were charged for 11 drinks. They had 11 drinks. One customer was charged for 8 drinks when he only drank 4. Waitress stated that there was 19 drinks served so 11 drinks were paid for and the remaining 8 were owed. Recommendation: establishment should keep track of who ordered what not the amount that was ordered. Waitress gave the last person to leave the bill for the 8 drinks when he only had 4.