Hi there @Dierenapotheek. 

Welcome to the Community! Very sorry to hear you’ve had issues with payment! 

You can always request an invoice inquiry with Support by using this link!  I hope everything gets sorted out!

Thanks for participating in the Community,

-Taylor 

Hello Taylor, thank you very much for your reply!

Hello, 

I have 2 klaviyo account one which we pay and the other one not yet and I would like ito upgrade the plan to a paid one.

Despite having enough funds and correct billing information (same as the paid account), our credit card is not accepted and is declined. I have been trying many times and still nothing, Can anyone help me?