Can you fix it without breaking my live store or risking card data?

Yes, this is the whole point of working through a payment specialist. We work via the gateway’s tokens and webhooks, never raw card numbers, so your PCI / SAQ-A scope stays intact. Changes go through staging, get regression-tested across auth / capture / refund / 3DS, and ship with a rollback plan. Your existing successful orders and customer data are never touched.