Hi Sean, you may need to reach out to the vendor that does the scheduling for these. When I've taken Microsoft exams that vendor was PearsonVue. I haven't seen the text of your email so can't say for sure but if they're giving you an option for a re-take then they probably won't charge you. They've done this to me before when my system or labs have crashed mid-exam. It's a pain but at least they realize that this happens so they're quick to offer the re-take.
We don't have any control over these on these forums. https://learn.microsoft.com/en-us/learn/certifications/exams/ms-700