Insignia CD400 DAB Issues

[Dud2020]

Hi fellas. I know the CD400 threads have been done to death, but please dont shoot me for one more 
Last week I got my first ever Vauxhall Insignia. 2012 cdti SE, with the CD400 head unit.
I know the DAB signal is hit & miss in the UK, but my signal goes from perfect, to non existant within driving 20 feet. Our DAB signal in the house is bang on, so Id say we are well within transmitter range. Ive seen on here the CD500 is more superior but until then, could anyone point me towards a quick fix please? Is it worth spending a few quid on a shark fin aerial? Is it possible a signal booster would help? I've been unlucky enough to own Fords for 10yrs, so at the moment im a Vauxhall Virgin. Thanks in advance
Dud

[Rusty2009]

is it dropping out and coming back like going through a dead spot or just gone until you stop again?

[Dud2020]

[attachment=1201]

Rusty2009 pid='53906' dateline='1607326007']is it dropping out and coming back like going through a dead spot or just gone until you stop again?

Hi mate. Thanks for your reply. It was dropping out...comimg back...searching for the station etc, and it got a right P.I.T.A! However, I had an idea. I removed the aerial from the roof, and it seemed to be a metal insert (obviously) with a hard plastic sheath around it. I had a brainwave, and made thickish copper coil from the thread which screws into the base on the roof, then wrapped it many times around the aerial over the plastic sheath. Ontop of that, I wrapped a layer of foil from bottom to top, and screwed it back on....Its worked perfectly. No DAB issues since. I then tightly wrapped black tape over my 'Mod' and to be honest, it looks fine, although slightly wider than it was
[attachment=1203]
   

Note- Still need to take a pic of finished job