Incorrect portion sizes

Went to atasca yesterday 06.09.17 and ordered the queen prawns meal which consists of 6 queen prawns for R210. When the meal arrives i have noticed 5 of the prawns were the correct and 1 was very small which could have never been a queen prawn. Called the waitress, told her the problem, she took the plate to her manager, manager took it to the chef, manager came back to us with the plate only to tell us that all the prawns were taken from the same box and they would enquire about it with their supplier. After that the problem was still not solved. If i paid for a queen prawn i should get what i paid for. The situation was handled pathetically and there was basically no outcome.