Used to work for them. The best you're likely able to manage is to ask them to retroactively apply one of the data roaming package
Given the amounts involved, it will at least require the approval of the manager on duty.
Best bet is to avoid any sort of confrontational behavior. Admit that you screwed this up, indicate that you only need it as a one-off solution, and will make sure to make arrangements in the future to either get a package or block the feature in the future.