I just called Apple support and escalated this issue to their senior management. I ahve the same issues (4 credit cards got decliend, and new Apple account is not able to enroll at all). He basically said I've already tried all the method they can suggest (trying different credit card and using a different Apple ID). Anything else he said is internal and is not willing to disclose. He dose not admit it's Apple's internal issue at all. As soon as I said "it means it's not working" or "when will this resolved", he immediately replies "that's not what I said" or "I didn't mean that". No responsibilities at all. Shame on Apple!