There's a free app called GPS Information from EXA Tools, which will tell you what satellites it can see from your location. If it gives the correct Lat and Long for your location, then it would appear to be your SatNav at fault.
Went in to Nissan Nottingham yesterday. They "fixed" it. I turned right, heading, south along the road. The satnav carried on straight, through a hedge, across four lanes of traffic, through a Honda dealership and smashed into B and Q. I turned around to report it to Nissan, then I went back the same way home, south and then east. The satnav went west-north-west.
The Leaf went in on Monday and of course I had to ring up on Thursday to find out what was happening to MY CAR. It was a "big job" to get to the antenna and then they had to order a replacement from Amsterdam and that wouldn't arrive until Monday (because overnight shipping isn't a thing). I can keep the ICE courtesy car (which I hate) and the chap said he'd extend the insurance (would I have been uninsured if I hadn't rung? You betcha!).