Finally, when I could get hold of support via chat, I had to play 20 questions with them to prove I was an actual business and supply all my business documentation that proved such. The issue occurred because my customer’s debit card purchase was being blocked by his bank, but we didn’t know that at the time. Since I tried to process it a couple of times - while on the phone with him - Shopify apparently suspected my new account was fraudulent and I was trying to force a debit card payment through.
It wasn’t until my customer got a call from his bank, did we learn that’s who was blocking the transaction. By that time, Shopify’s legal department had already shut down my account. It took the better part of a week to get my account re-established. Moral to the story is, if you’ve established a new Shopify account don’t try to manually process an order on your end. Let the customer make the order from their end.