Getting order wrong

On a number of occasions our staff order food from Flame Diner at lunch time. We phone the order through so that it gives them time to make the order and not put them under pressure. The last three times that we have ordered they have got my meal wrong even though they were very simple meals. The first time I ordered a Bacon & Cheese burger and got a Cheese and Mushroom Burger. The second time I ordered a Chicken salad and when I got it there was no Chicken in it just lettuce, tomato etc. The last straw was today when I ordered a double hot dog WITH NO Sauces. What I got was a double hot dog with mustard, tomato sauce and the whole thing was soggy. Unfortunately we send somebody to pick up the food and they don't know what everybody has ordered. I don't recommend Flame Diner and won't be eating their food again.