After nine years stress free driving in the reliable Rangee, the sat Nav map is indicating my location as on the wrong road?

The Arrow on the touch screen showing my current position is 1 mile out of sync.

I have recalibrated the screen 3 x's initially system works, yet as soon as I switch off the car and restart later, I am back to square one, I have also disconnected the negative terminal on the battery to reset the cambos.

Any one else experienced this glitch? Last thing I need is to stick a Tom Tom on the windscreen?? Diver Bryn

Previous Transport:
Honda CB250n
Toyota Starlet
Renault Fuego 2 ltr TX
Fuego Turbo
BMW 528i
Escort RS Turbo
Capri 2.0 L Ghia
Kawasaki GT750 P4
Mini Metro
Ford XR2
Volvo 740 TDi Estate
Mondeo Tdi
Volvo V70 Tdi
Mercedes E300 TDI
Mercedes E320 Cdi
Mercedes S320 Cdi
Land Rover Discovery 3 TDV6
Mini Cooper Diesel
Mercedes Vito Van 111
Range Rover TD6
VW Golf 2ltr GTD 2015 Year
2016 Audi Q7 Sline 3ltr 272Bhp

Probably water ingress on the roof Arial. Had same on a Jag XKR with same system. You may need a new arial unit.

I am sure one or two have had problems with the sat nav aerial try a search? I think there was a cost effective aftermarket solution, Unless I am imagaining again! Mine was a blue one!