faulty speedometer reading (too high ) and erratic return.

Hello, Replacing the speedometer or instrument cluster is not something we have an estimate for yet, so it would need to be quoted by a repair facility. Erratic return: this sounds like the reading from a code scanner, but those phrases they provide are non-generic. Each different company will have their own phrase there. If you have a trouble code, let me know. Also, it is unlikely that a repair facility will replace the vehicle speed sensor and speedometer/instrument cluster without diagnostics being performed. That could lead to a very unsatisfied customer, wasted time and cost, and the same problem existing after repair.