Netstar false alarm

I constantly get messages that my tracking system, Telesure stardrive bronze SAS EWS TAG with sleuth Nano II, in my Porsche has been activated. The standard message when I call Netstar is that the battery on the remote needs replacement on a remote that was 3 months old when the first false alarm was activated. I changed the battery and a technician came to assess the tracker on the vehicle. Only to tell me that if a jamming device is near the vehicle this will happen, amazingly whilst the car is in the garage in an estate. Netstar simply does not solve the problem. I notice Kabelo also had such a problem two days ago on Hellopeter.