Hot TTN bluetooth

I logged some time ago that my TTN BT could not cope with the 'summer heat' sitting on my black dash. In order for it to run 'cooler' I even tried the small 'paper hut' recommended elswhere. This is the reply I got from TomTom re this issue:

Dear....,
Thank you for contacting TomTom customer service.

If you have the GPS receiver on the dashboard in the sun this can cause the receiver to
lose signal. The GPS receiver has no problem with temperatures around 25- 30 degrees.
Try and place the GPS receiver by the air conditioning.

What do I say to that ??? I have no aircon in the car. Does this mean that I can only use the TTN B/T on a cloudy/rainy day, in the winter or during the dark hours ????

Any ideas of a reliable solution would be most welcome, all I can think of would be to buy an external aerial and chuck it in the gve box but that would mean spending more money on a product that in my opinion should be built to cope with these conditions.