2018 Porsche Cayenne - Bluetooth connection issue

The Bluetooth is not working correctly .... . The iphone disconnects when I try to make a call. The call is still connected within the phone, but the car drops the connection to the iphone. My iphone has been checked by Apple including them sending me a patch and them downloading all the diagnostics off my phone straight after the fault. Apple have confirmed there is nothing wrong with my phone. It also connects perfectly to two other new Cayenne's, a 2019 base model and a new 2019 Cayenne coupe. In addition, sometimes the media music downloaded is duplicated within the Porsche system. 

The dealer is saying its a known issue, but Porsche are waiting on Apple to send the info to them. Bearing in mind my phone works in two latest Cayenne's then I suspect.

They swear my car is running the latest software and i know my phone is. Despite my phone working on the other two Cayenne's this means nothing apparently because they are not hybrid's and the system in the other two cars is different ..... something I find hard to believe. 

My gut feeling is that there may be a group of cars with a faulty Bluetooth Module, but Porsche wont want to authorise changing the whole computer module on these cars as they can 'blame' a 3rd part ie Apple.