DNX525DAB Bad Reception - Traffic Live

Hi everyone

This is my first time. Sorry my English was not good because I am profound deaf.

I am fed up with Garage, Kenwood and Garmin have problem with my Sat Nav.  Let me explain.  I bought brand new Skoda Fabia 1.2 TDi Greenline Aug 2014.  It was fab mile per gallon about 80..... Sat Nav of DNX 525 Dab Kenwood, was fab.... good with Traffic Live.   Last year August, something happen with Sat Nav, not work properly. So I reset on Sat Nav then afterward Traffic Live was not always work properly.   I went to garage few times to sort out problem, Been emails to Kenwood and Garmin many times.  They cannot find what problem... Last week, I demand replace new Sat Nav unit....   Now it still problem with Traffic Live,    You might know on screen  bottom right side green circle which it show Traffic Live work but What I got is grey, sometime work, sometime not work!!   Advice me what shall I do next? 

Bob