Due to not being an official META business partner yet, we are working with our partner 360Dialog. You require a 360Dialog Account to be able to to be able to use a "WhatsApp Business Plattform" account.
The subscription fee for such an account costs €25,00/month and is billed monthly on the day of the creation of the account.
🚨 You can log in to 360Dialog -> Funds -> Transfer the funds back to your account, especially important, in case you migrate provider, directly to Meta Billing.