Included Devices: 21 / 25 but i got an invoice of 20.25 usd

hi,
i have:
Included Devices: 21 / 25

and still got invoice of 20.25 usd and deducted from my VISA,
can i know why,
and what is the support email?

Hi! For billing questions or help reviewing your invoice, you can either:

We’re happy to assist further!