I try to add 25 computers but I get this?

I cannot add 25 computers to my suscription, but when I select "125" I see this text:

"Your current Central subscription will be cancelled and rebooked at a lower rate. This will also restart your service period."

What this means? it's confusing because I already pay for 100 computers in august and my current suscription its valid until august 2025.

Y pay 550 USD in august for 100 computers, now they want to charge me 777 usd for 125 computers, but how this works? I already pay 550! they will refund me the 550usd and then charge me 777 usd? or they will charge me just the difference.

is not clear, and there is no email / chat support!