I have often written to restaurants and food outlets asking that lower carb and gluten free options are introduced to their menus, explaining some of the issues many people with diabetes are faced with when eating out.
Restaurants usually have a set menu, unless you go for a la carte of course, and its at their discretion whether they will swap a food item or not.
I dare say the staff member felt out if his/her depth, probably has no idea of a diabetics food requirements, didnt quite know what to do and then to top it all gets overruled by his/her manager who hasnt got the foggiest what really happens on the shop floor.
Fair enough to ask that chips are removed and replaced with mushrooms, but to ask for a mushroom and then a tomato as well and oh, wait a minute, I dont eat eggs either.......probably in a crowded restaurant with other customers waiting to be served, must have been a stressful situation all round but imagine if every customer were to ask to swap food items?!