iPhone 6+ and Bluetooth - WV Up!

Hi,

I just bought a new car, a Volkswagen Up! (2015) and I´m having some serious problems with my iPhone after each time I connect my iPhone to my car with Bluetooth.

I can connect my iPhone via bluetooth to my VW without any problems, it connects automagically every time I enter my vehicle.

But a huge problem occurs when I leave my vehicle:
After a drive with Spotify playing on the speakers throught BT on my iPhone 6+ I get serious problems with iOS on my iPhone.
(This happens when I leave the car, I know I´m not connected with BT to my car when I´m home, because of the range)

When I get home and out of reach of the car, iOS gets really buggy:
1. Sound stops working - Lock sounds and other sounds disappear
2. Unlocking the iPhone is a nightmare - it takes at least 5 seconds before the screen turns on when using Touch ID or the old-fashioned slide to unlock-feature.
3. When the iPhone is unlocked - its a challenge to even lock the iPhone - Screen does not always respond when I click on the sleep button.

4. I have two "pages" of apps on my iPhone, when Scrolling from page 1 to page 2 - its often bugs the entire springboard, meaning: Instead of "snapping" the apps into the right place when swiping left, the entire page and be misplaced, in other words - a row of apps can start from the middle of the screen instead of to the left.
( That was hard to explain, but: u have 4 rows of icons on the screen, when this bug appears the first row is blank, there is nothing there, meaning I only get 3 rows of apps, starting from THE MIDDLE of the screen )

I am almost 100% certain that it is my car + iOS/Bluetooth that is the problem, this is because I have never experienced this before - and it happends every single time I go out for a drive.

Turning Bluetooth OFF after a drive does not fix the problem.

Turning my cellphone completely OFF and back ON again - Fixes the problem untill the next time I get back in my car.

My iPhone is running the latest iOS possible (not Beta)

How can I fix this problem?

Thanks for any help