Resolve Claude Subscription Payment Issue

I’m ready to upgrade my Anthropic Claude account so I can rely on its Pro or Max features for research and everyday questions, but my payment card keeps getting declined during checkout. I already have an account and simply need to complete the subscription—no additional seats or team setup required... (Budget: $30 - $250 USD, Jobs: Account Management, Billing, Customer Support, Payment Gateway Integration, Payment Processing, SaaS, Technical Support, Troubleshooting)