Time to retire the sat-nav
I'm sorry old friend, but you've had it. It was bad enough that you started to tell me I had arrived at my destination about 60 seconds after I actually had arrived, or that you would tell me to 'Turn right now' only to then tell me you were 'recalculating' after doing so.
Or perhaps it was the massive and blatant bad routes you had selected (when going to North Wales it always wants me to go via Runcorn rather than down the motorways) and regardless if I have you set to fastest route or most economical route you will always get it wrong. Not being able to locate satellites until about 4 mins into the journey does not help matters either, or telling me I need to turn as I'm alongside the junction..
In your younger days you were not always like this, but I suspect the years of firmware and map updates have just bloated you out to such an extent you poor 5 year old processor is now quite beyond what I need you to do, and no amount of adjusting the settings is making it any better.
So, my dear old Garmin Nuvi 255W is now being outdone by Google Maps and CoPilot running off modern mobiles and will be retired to the 'junk tech' drawer at home. I don't think I'll buy another stand-alone sat-nav now. Still, it'll be interesting in 20 years time to see an exhibit of them in a motor museum somewhere in a display of motoring curios.