Can't help re the speedo, but theres a trick with the dual climate controls where the right hand display will show your speed. Might get you out of trouble till you get it sorted.
Think you hold 'econ' and the 're-circulated air arrow' buttons together, turn the left control clockwise until the left hand display shows 19-0, turn the centre control clockwise once until the display shows 19-1, now the right hand display will show a corrected mph speed. To come out of this function just press the 'econ' button again.
I'm sure if thats not spot on someone will correct me!