Thanks for your message.
From the screenshot you sent it looks like the charge of $419 is for one month (4th Dec - 4th Jan $349) + (now until the 4th of Dec $70). Your billing period is from 4th - 4th, so if you upgrade before that date it is simply charging for the extra days before that date.
If you need any more help please feel free to open a ticket from the contact support option on your dashboard.
Hi, I want to subscribe to the 2.5M request plan, but when I go to make the payment it wants to charge me $420 instead of $350. Any idea why?