Hi cmathis0231,
I see it's your first post here, so welcome to the community! Thank you for posting. Bare65 covered your first concern--your bill is generated every month on the 8th. When you have your credit card on file with us, it is charged on the bill generation date. The due date of the 18th only applies if you were on invoice pay; it gives time for your mailed payment to get to us.
Regarding any unusual charges, I pulled up your billing history-- charges and payments have been consistent since last summer (kudos!), and the only bill increase I see was on the February bill, which was due to the $9 data token purchased, but that bill was only charged once.
Other than that, your March bill has gone back to the usual monthly charge. If you're seeing any additional/questionable charges from HughesNet, please private message me your financial statement that reflects these multiple charges.
You can compare this to your HughesNet bills, which can be viewed online. Here are instructions on how to do that.