A) Don't store credit card information
B) In order to do their job, programmers have access to the database so Magento Admin access protects nothing.
So, if you want full protection, you give them a sanitized database to work with. They should be working on a development server, not your live site anyway.
You will have to trust someone to move the changes from the development server to live.
There are tools available that allow you to do development database dumps that are cleaned of customer data.