I was unable to reproduce your issue using the latest stable version 3.7.6, therefore I recommend you to open a support ticket here: * http://helpdesk.phpfox.com/
1. An admin made an account for support or a developer to use and forgot to tell you. Check with your other admins.
2. An admin accidentally moved a spammer to admin user group instead of banned.
3. You have Younet add ons and they are again allowing people to log in as other people perhaps. They have fixed that issue about 4 times now and if it is back you need them to fix it if you have the add ons that have been impacted by this in the past.
4. You went on an unsafe site and gave info to unsafe people.
well, that would make no sense.. if this is a feature that actually should work with the standard phpfox solution... this just can be a little change in code.. I can guess there is a workaround, without upgrading my version...
Nope, It should work if buyers have palpal account. If you want it to work with credit cards and buyers do not need to have paypal account then you have to set up your paypal account and pay them like $10/month(not sure). This way, paypal will collect the money for you even if the buyers is not a paypal account holder.