I know this is an issue most vegans will face sooner or later, but this isn't about veganism, honestly. It is purely about accommodating different needs.
Do you think they would be more understanding if you had coeliacs or some food allergy? If you don't want to be known as the straw vegan, you can argue that it's not about your beliefs, but about making the work environment friendlier and more pleasant to work at.
If it's a big office, then it is likely there are other veg*ns working there. Raising awareness would be a way to get their attention, since businesses like numbers. Maybe a friendly email signed by a few dozens of you will make them get the message without much discussion.
Always keep in mind this question: "what's in it for them"? Can they hop at several hype trains at the same time? Maybe vegan and gluten-free, or vegan and light/diet, or vegan and exotic, whatever floats their boat. Once they accept the first suggestion, it's bound to get easier from there on.
Don't push it too hard. Maybe they'll start offering 3 vegan options only on Fridays as an experiment. Don't get disappointed, take it as a win. Eat there, invite coworkers, give them feedback.
At school, it took us years before the cafeteria would offer vegetarian lunch options. Maybe we could have pushed it harder and got it sooner, but, then, we wouldn't be able to accomplish everything else we wanted: allergens started being listed on the menu, there were also vegetarian dinner (and dessert) options, every vegetarian dish was converted to vegan, and the cafeteria stays open for longer.