I am sure when you need to connect to ur vehicle sat u can be visible then and then turn the visibility off. Another thing you can do is go to ur Bluetooth and click on the 3 dots on the right hand side and click advanced and and choose block pairing request.
Interesting one. I don't know of any British Telecom devices that will try to connect with a device. I don't think I know of any British Telecom hardware that's Bluetooth to be honest.
Are you sure it's British Telecom? Some devices list themselves with a BT prefix that means Bluetooth