Klaviyo Customer Service Team

Hi there @Baseus, 

Welcome to the Community! I apologize you’ve waited so long to hear from our Support team! 

I was able to take a peak at your ticket and saw that you are inquiring into why your billing jumped from $650 → $1,300. A possible reason for the upgrade could be that you had  auto upgrade turned on in your account and you either did one of the following actions:

• Reach your plan's message or profile limits (e.g., if your plan allows for 200 profiles, but you try to send to 300 profiles).
• Schedule a campaign that will send to more profiles than your plan allows.
  • Note: Auto-upgrade can occur even if the campaign is scheduled to send in a future billing cycle.

While you can downgrade your plan, downgrading always takes effect the following billing cycle. You will finish out your current month's plan before your plan changes. Thus, we do not refund downgrades, as stated in our Terms of Service. 

I will reach out to our finance team team on your behalf and sorry again for this experience! 

-Taylor