experia z5 bluetooth

[jabem]

hi everbody i need help please

i have an xperia z5 and when i am in sync thro' bluetooth on my ford radio and i'm in coversation using bluetooth the call keeps dropping 

i have stripped it back to factory settings but no better 

my son's z4 works perfectly in the car

any solution please it's driving me crazy (apoligies for the pun

[teethiob]

My experiences with car entertainment systems and phones have teached me that you never know do they work together or not. Example car is VW and Sony Z5 drops off during calls, both side just cant hear each other. At the same time I can pair Z5 to listen music from phone without problems which is not happening with Samsung Galaxy A8 but A8 has no problems to use hands free phonecalls. Xperia X worked fine on calls and multimedia. Best results giving old Nokia Symbian keypad phone C5-MP5 VW car is from 2014. I tried everything to get Z5 work without those dropoffs but no luck, just use other phone or buy another car. Thats the joy of bluetooth technology.