Hello,
I completely understand how frustrating this issue is, especially when it involves payments and work invoices that are hindering your projects, and the slow response time from email support.
Since the problem involves Stripe payment rejections and cards not being accepted despite being valid, here are some steps and points that might explain or help resolve the issue:
Check your card issuer: Often, your local bank automatically rejects international or online transactions to protect your account. It's a good idea to contact your bank's customer service to confirm that there are no restrictions on online or foreign currency transactions for platforms like Vercel/Stripe.
Try a different card or payment method: If possible, try using a different credit card (from a different bank or a virtual card) or use your PayPal account if it's available as a payment option.
Deal with automated support responses: Regarding slow or automated email responses, Billing & Payments tickets usually start with automated responses (bots) to verify the details of the problem. For a quick human response, try replying directly to the automated message with precise details (such as the last four digits of your card, the time of the payment attempt, and the exact error message). The ticket is often escalated to a dedicated finance officer within hours.
I hope your billing issue is resolved soon so your business can return to normal operations!