is ti expensive? Driving my Picasso - speedo reads 32mph, I know I'm not traveling at that speed, more like 20mph.
Speedo will jump from 5mph to 17mph and when I brake, the speedo does not decrease at all until I stop, then it reverts to 0mp. It is definitely wrong - but how to fix? Can I do it myself by purchasing a new unit or something or do I need to take it to a garage? Any ideas on cost?

Thanks