Question for z series owners about calls and functions

[fwd4g63]

Hey all. I have had a few of the avic products in the past. I have had a z1 and a z3. I currently have a f90t with f910 upgrade, that i am not happy with at all. I have called and asked pioneer and they really cant tell me or want to give me a direct answer. I am looking for a unit that does not have the phone or bluetooth issues i currently have. Mainly if im on the phone, all functions of the headunit are rendered useless. I would like to access the navi menu while on the phone. ALso, if i am on a call and get a second call and switch over to it, the unit will not hang up when the call is completed. I have to stop the car, turn it off and reboot the entire system. Also the software seems to be pretty unstable. When you push on functions, sometimes it doesnt do anything at all or it is very delayed. The phone seems to be the major issue i have with the unit. Any model advice or other info of would be great.