Oh god, I don't know how to be a person.

Oh okay, so here's a thing: how do you be assertive and clear to people without sounding like a dick? I should know how to do this, absolutely, because I am in the service industry, and have been for a long time. This should be a thing that I am good at. But I just don't know how to do it. Okay, so an example of what I'm talking about is such: I am about to order dinner for delivery from Seasons. I prefer to order it online, because ordering online allows me to customize the order so that they have everything I want already written down, all the work done by me, and I don't have to give a long-winded order to some poor apathetic person on the phone. I frequently get a chicken cheesesteak wrap with grilled onions, mushrooms, green peppers, american cheese, and salt and pepper. And I like it to be toasted. That might sound kind of long-winded, but that's not the problem. They've gotten that right several times. The kicker is that I like my chicken cheesesteak wrap WITHOUT the chicken. So basically just veggies and cheese in a wrap. So I include a note that says "No chicken, please! Just veggies and cheese." They've done this successfully several times (I eat Seasons a lot). Once or twice, they called me and were like "So...no chicken? Just...veggies and cheese?" and I'm like "Yep!" and then they're like "uh.....but...well...okay." and then it's fine, and I enjoy my delicious food some 45 minutes later. I don't think I'm being super unreasonable; I'm even willing to PAY for the chicken I'm not eating. Now, for some reason, recently they've been having trouble with this order. First, they sent me exactly what I ordered, except they left the chicken on the wrap. Which is okay, because I'm not a vegetarian; I just prefer my wrap sans chicken. It's less greasy, and more...tastefully(?) pleasing to me that way. So whatever, I ate it and the next time I ordered, I was shouty about the chicken ("NO CHICKEN, please. JUST VEGGIES AND CHEESE"). Still polite, just a little larger text. So instead of just leaving the chicken off my wrap, they created their own invention. I'm assuming they thought that I was a vegetarian, and thought that I was under the impression that all I could get was what I ordered, so decided to give me a chef's tasting menu veggie wrap creation. They threw broccoli on that bitch, and sweet peppers (which I HATE), and instead of american cheese, gave me mozzarella. It definitely wasn't someone else's order or something, because that's not anything remotely similar to anything on the menu. It was definitely them thinking that I couldn't possibly actually WANT what I ordered, and that what they put together would taste WAY better. I'm not a dick, so I picked the sweet peppers off and ate it without complaint. But now I want to order again, and I want to make sure that there isn't a repeat of last time. So my question is this: how do I do this without being a dick? Do I call and order my obnoxious and complex order over the phone, and make some person take all that information down? Do I order online and then call and verify that I want EXACTLY what I ordered? Because if someone called ME to confirm they want EXACTLY what they order, I would definitely roll my eyes, hang up, and yell "DICK!!!" Am I just a dick in general for having such a high-maintenance (?) order to begin with? OR. Maybe I'm just a freak for worrying so much about this altogether. It's not like my minor annoyingness is going to ruin somebody's day. I'm not yelling at anyone, or even copping a 'tude. I'm extremely polite about it either way, and I tip generously. So, who cares I guess. Except I still DO care. Maybe I should just be medicated. SIGH.