Where to stick my tag?

Hi,

Has anyone encountered this problem?  Sanef recommend the Autoroute tag goes behind the rear mirror in the shaded area; reason being this area would be guaranteed heat reflective glass free.  I own a Volvo XC60 the area behind the rear mirror is occupied by safety camaras for the city driving and blindspot function.

Sanef have advised l seek help from Volvo; l have emailed them but just wondered if anyone has encountered this problem before...and if so where did you stick your tag?

Cheers,

Murdy