Buying Steem with a credit card - How to solve the charge-back issue?

From earlier posts and comments, it seems the number one problem with accepting credit cards for Steem sales is the issue with fraudulent charge-backs.  A person is able to buy cryptocurrency with a credit card or Paypal, then ask the issuing bank for a refund.  They get their money back and keep the crypto.

How to get past the fraud and charge-back issue?  
I am not an expert on banking, but I thought I would throw this out there:

A person buys Steem with a credit card at 2x the price, They get their Steem.  90 days later, they then will receive the same amount again.  Couldn't price fluctuation be solved with the 2nd payout of Steem held in a smart-contract?

If price fluctuation is an issue, one could use SBD.  A person would receive half the amount they purchase immediately, the other half after the charge-back option expires.  This could be done by smart-contract.

This isn't perfectly ideal, but it is a way to get Steem right away with your credit card. You would get 50% immediately, but would have to wait a certain amount of time for the other 50% purchased.   This seems better that selling powered-up accounts that would require 90 days to fully turn into liquid steem.  It also allows users to buy who already have an account and/or Steem.

If there is a charge-back, the 50% in the smart-contract is never sent to the account.  If the time passes, it is signed off and the Steem is released.

Still, I understand there is a risk for a person/company losing 50% of a purchase.  Perhaps there is a better formula for percentages, rate of release, etc.

I am just brainstorming here, I know this is roughly laid out.  Thoughts?