I stopped on the M1 to get some coffee at the weekend and left my phone in the car by the gear stick (covered up) and when I came out of the coffee shop I could hear the beeper and see the indicators flashing, today I dropped the wife at the local Vauxhall dealer and left the phone in the same place with the same result, normally I do not leave the phone in the car but thought it might be of interest.
To prove the interference I tried it on the drive and it did it again.
Just in case anyone else has an issue
Pete