Blackberry security

How do I prevent someone from remote accessing my blackberry phone from their PC? I believe my phone is being remote accessed by an individual. My service is not on a corporate plan, I’m a private owner. I do not own a PC anymore so its extrememy frustrating trying to get help when I can’t access help via a PC. PLEASE ANY SUGGESTIONS ARE WELCOME! I have a Blackberry Curve 8320 thru T-Mobile.