The best thing you can do to protect yourself is to:
1. NEVER allow anyone that you do not know to remote into your computer
2. NEVER call 800 numbers from email or popups
3. Ignore emails claiming to have charged your credit card. Check you account instead
4. If the person is insistant, abusive or threatening, it is probably a SCAM
If you have fallen for a scam, immediately power off your computer and reach out for professional help.