I've recently started to go into London more often and so rely on satnav more than previously. I can't find any way to make the 6250 choose motorways and major roads by preference. Going from NW London to SE it will always try & take me along unsuitable roads through the centre where the previous satnavs I've used (a Co-pilot and a cheap £45 EBay one) will aim for the M25 if it's flowing ok. This is going to get me into trouble soon and I'm seriously thinking of ditching this quite expensive device. Any suggestions please?